view tests/test-status-color.t @ 37631:2f626233859b

wireproto: implement batching on peer executor interface

This is a bit more complicated than non-batch requests because we
need to buffer sends until the last request arrives *and* we need
to support resolving futures as data arrives from the remote.

In a classical concurrent.futures executor model, the future
"starts" as soon as it is submitted. However, we have nothing to
start until the last command is submitted.

If we did nothing, calling result() would deadlock, since the future
hasn't "started." So in the case where we queue the command, we return
a special future type whose result() will trigger sendcommands().
This eliminates the deadlock potential. It also serves as a check
against callers who may be calling result() prematurely, as it will
prevent any subsequent callcommands() from working. This behavior
is slightly annoying and a bit restrictive. But it's the world
that half duplex connections forces on us.

In order to support streaming responses, we were previously using
a generator. But with a futures-based API, we're using futures
and not generators. So in order to get streaming, we need a
background thread to read data from the server.

The approach taken in this patch is to leverage the ThreadPoolExecutor
from concurrent.futures for managing a background thread. We create
an executor and future that resolves when all response data is
processed (or an error occurs). When exiting the context manager,
we wait on that background reading before returning.

I was hoping we could manually spin up a threading.Thread and this
would be simple. But I ran into a few deadlocks when implementing.
After looking at the source code to concurrent.futures, I figured
it would just be easier to use a ThreadPoolExecutor than implement
all the code needed to manually manage a thread.

To prove this works, a use of the batch API in discovery has been
updated.

Differential Revision: https://phab.mercurial-scm.org/D3269

  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > color = always
  > [color]
  > mode = ansi
  > EOF
Terminfo codes compatibility fix
  $ echo "color.none=0" >> $HGRCPATH

  $ hg init repo1
  $ cd repo1
  $ mkdir a b a/1 b/1 b/2
  $ touch in_root a/in_a b/in_b a/1/in_a_1 b/1/in_b_1 b/2/in_b_2

hg status in repo root:

  $ hg status
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)

  $ hg status --color=debug
  [status.unknown|? ][status.unknown|a/1/in_a_1]
  [status.unknown|? ][status.unknown|a/in_a]
  [status.unknown|? ][status.unknown|b/1/in_b_1]
  [status.unknown|? ][status.unknown|b/2/in_b_2]
  [status.unknown|? ][status.unknown|b/in_b]
  [status.unknown|? ][status.unknown|in_root]
HGPLAIN disables color
  $ HGPLAIN=1 hg status --color=debug
  ? a/1/in_a_1 (glob)
  ? a/in_a (glob)
  ? b/1/in_b_1 (glob)
  ? b/2/in_b_2 (glob)
  ? b/in_b (glob)
  ? in_root
HGPLAINEXCEPT=color does not disable color
  $ HGPLAINEXCEPT=color hg status --color=debug
  [status.unknown|? ][status.unknown|a/1/in_a_1] (glob)
  [status.unknown|? ][status.unknown|a/in_a] (glob)
  [status.unknown|? ][status.unknown|b/1/in_b_1] (glob)
  [status.unknown|? ][status.unknown|b/2/in_b_2] (glob)
  [status.unknown|? ][status.unknown|b/in_b] (glob)
  [status.unknown|? ][status.unknown|in_root]

hg status with template
  $ hg status -T "{label('red', path)}\n" --color=debug
  [red|a/1/in_a_1]
  [red|a/in_a]
  [red|b/1/in_b_1]
  [red|b/2/in_b_2]
  [red|b/in_b]
  [red|in_root]

hg status . in repo root:

  $ hg status .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)

  $ hg status --cwd a
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)
  $ hg status --cwd a .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_a\x1b[0m (esc)
  $ hg status --cwd a ..
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../b/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../b/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../b/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../in_root\x1b[0m (esc)

  $ hg status --cwd b
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)
  $ hg status --cwd b .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b\x1b[0m (esc)
  $ hg status --cwd b ..
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../a/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../a/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../in_root\x1b[0m (esc)

  $ hg status --cwd a/1
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)
  $ hg status --cwd a/1 .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_a_1\x1b[0m (esc)
  $ hg status --cwd a/1 ..
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../in_a\x1b[0m (esc)

  $ hg status --cwd b/1
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)
  $ hg status --cwd b/1 .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b_1\x1b[0m (esc)
  $ hg status --cwd b/1 ..
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../in_b\x1b[0m (esc)

  $ hg status --cwd b/2
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/1/in_a_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4ma/in_a\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/2/in_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4mb/in_b\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_root\x1b[0m (esc)
  $ hg status --cwd b/2 .
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b_2\x1b[0m (esc)
  $ hg status --cwd b/2 ..
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../1/in_b_1\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4min_b_2\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4m../in_b\x1b[0m (esc)

Make sure --color=never works
  $ hg status --color=never
  ? a/1/in_a_1
  ? a/in_a
  ? b/1/in_b_1
  ? b/2/in_b_2
  ? b/in_b
  ? in_root

Make sure ui.formatted=False works
  $ hg status --color=auto --config ui.formatted=False
  ? a/1/in_a_1
  ? a/in_a
  ? b/1/in_b_1
  ? b/2/in_b_2
  ? b/in_b
  ? in_root

  $ cd ..

  $ hg init repo2
  $ cd repo2
  $ touch modified removed deleted ignored
  $ echo "^ignored$" > .hgignore
  $ hg ci -A -m 'initial checkin'
  adding .hgignore
  adding deleted
  adding modified
  adding removed
  $ hg log --color=debug
  [log.changeset changeset.draft|changeset:   0:389aef86a55e]
  [log.tag|tag:         tip]
  [log.user|user:        test]
  [log.date|date:        Thu Jan 01 00:00:00 1970 +0000]
  [log.summary|summary:     initial checkin]
  
  $ hg log -Tcompact --color=debug
  [log.changeset changeset.draft|0][tip]   [log.node|389aef86a55e]   [log.date|1970-01-01 00:00 +0000]   [log.user|test]
    [ui.note log.description|initial checkin]
  
Labels on empty strings should not be displayed, labels on custom
templates should be.

  $ hg log --color=debug -T '{label("my.label",author)}\n{label("skipped.label","")}'
  [my.label|test]
  $ touch modified added unknown ignored
  $ hg add added
  $ hg remove removed
  $ rm deleted

hg status:

  $ hg status
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1madded\x1b[0m (esc)
  \x1b[0;31;1mR \x1b[0m\x1b[0;31;1mremoved\x1b[0m (esc)
  \x1b[0;36;1;4m! \x1b[0m\x1b[0;36;1;4mdeleted\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4munknown\x1b[0m (esc)

hg status modified added removed deleted unknown never-existed ignored:

  $ hg status modified added removed deleted unknown never-existed ignored
  never-existed: * (glob)
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1madded\x1b[0m (esc)
  \x1b[0;31;1mR \x1b[0m\x1b[0;31;1mremoved\x1b[0m (esc)
  \x1b[0;36;1;4m! \x1b[0m\x1b[0;36;1;4mdeleted\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4munknown\x1b[0m (esc)

  $ hg copy modified copied

hg status -C:

  $ hg status -C
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1madded\x1b[0m (esc)
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1mcopied\x1b[0m (esc)
  \x1b[0;0m  modified\x1b[0m (esc)
  \x1b[0;31;1mR \x1b[0m\x1b[0;31;1mremoved\x1b[0m (esc)
  \x1b[0;36;1;4m! \x1b[0m\x1b[0;36;1;4mdeleted\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4munknown\x1b[0m (esc)

hg status -A:

  $ hg status -A
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1madded\x1b[0m (esc)
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1mcopied\x1b[0m (esc)
  \x1b[0;0m  modified\x1b[0m (esc)
  \x1b[0;31;1mR \x1b[0m\x1b[0;31;1mremoved\x1b[0m (esc)
  \x1b[0;36;1;4m! \x1b[0m\x1b[0;36;1;4mdeleted\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4munknown\x1b[0m (esc)
  \x1b[0;30;1mI \x1b[0m\x1b[0;30;1mignored\x1b[0m (esc)
  \x1b[0;0mC \x1b[0m\x1b[0;0m.hgignore\x1b[0m (esc)
  \x1b[0;0mC \x1b[0m\x1b[0;0mmodified\x1b[0m (esc)


hg status -A (with terminfo color):

#if tic

  $ mkdir "$TESTTMP/terminfo"
  $ TERMINFO="$TESTTMP/terminfo" tic "$TESTDIR/hgterm.ti"
  $ TERM=hgterm TERMINFO="$TESTTMP/terminfo" hg status --config color.mode=terminfo -A
  \x1b[30m\x1b[32m\x1b[1mA \x1b[30m\x1b[30m\x1b[32m\x1b[1madded\x1b[30m (esc)
  \x1b[30m\x1b[32m\x1b[1mA \x1b[30m\x1b[30m\x1b[32m\x1b[1mcopied\x1b[30m (esc)
  \x1b[30m\x1b[30m  modified\x1b[30m (esc)
  \x1b[30m\x1b[31m\x1b[1mR \x1b[30m\x1b[30m\x1b[31m\x1b[1mremoved\x1b[30m (esc)
  \x1b[30m\x1b[36m\x1b[1m\x1b[4m! \x1b[30m\x1b[30m\x1b[36m\x1b[1m\x1b[4mdeleted\x1b[30m (esc)
  \x1b[30m\x1b[35m\x1b[1m\x1b[4m? \x1b[30m\x1b[30m\x1b[35m\x1b[1m\x1b[4munknown\x1b[30m (esc)
  \x1b[30m\x1b[30m\x1b[1mI \x1b[30m\x1b[30m\x1b[30m\x1b[1mignored\x1b[30m (esc)
  \x1b[30m\x1b[30mC \x1b[30m\x1b[30m\x1b[30m.hgignore\x1b[30m (esc)
  \x1b[30m\x1b[30mC \x1b[30m\x1b[30m\x1b[30mmodified\x1b[30m (esc)

The user can define effects with raw terminfo codes:

  $ cat <<EOF >> $HGRCPATH
  > # Completely bogus code for dim
  > terminfo.dim = \E[88m
  > # We can override what's in the terminfo database, too
  > terminfo.bold = \E[2m
  > EOF
  $ TERM=hgterm TERMINFO="$TESTTMP/terminfo" hg status --config color.mode=terminfo --config color.status.clean=dim -A
  \x1b[30m\x1b[32m\x1b[2mA \x1b[30m\x1b[30m\x1b[32m\x1b[2madded\x1b[30m (esc)
  \x1b[30m\x1b[32m\x1b[2mA \x1b[30m\x1b[30m\x1b[32m\x1b[2mcopied\x1b[30m (esc)
  \x1b[30m\x1b[30m  modified\x1b[30m (esc)
  \x1b[30m\x1b[31m\x1b[2mR \x1b[30m\x1b[30m\x1b[31m\x1b[2mremoved\x1b[30m (esc)
  \x1b[30m\x1b[36m\x1b[2m\x1b[4m! \x1b[30m\x1b[30m\x1b[36m\x1b[2m\x1b[4mdeleted\x1b[30m (esc)
  \x1b[30m\x1b[35m\x1b[2m\x1b[4m? \x1b[30m\x1b[30m\x1b[35m\x1b[2m\x1b[4munknown\x1b[30m (esc)
  \x1b[30m\x1b[30m\x1b[2mI \x1b[30m\x1b[30m\x1b[30m\x1b[2mignored\x1b[30m (esc)
  \x1b[30m\x1b[88mC \x1b[30m\x1b[30m\x1b[88m.hgignore\x1b[30m (esc)
  \x1b[30m\x1b[88mC \x1b[30m\x1b[30m\x1b[88mmodified\x1b[30m (esc)

#endif


  $ echo "^ignoreddir$" > .hgignore
  $ mkdir ignoreddir
  $ touch ignoreddir/file

hg status ignoreddir/file:

  $ hg status ignoreddir/file

hg status -i ignoreddir/file:

  $ hg status -i ignoreddir/file
  \x1b[0;30;1mI \x1b[0m\x1b[0;30;1mignoreddir/file\x1b[0m (esc)
  $ cd ..

check 'status -q' and some combinations

  $ hg init repo3
  $ cd repo3
  $ touch modified removed deleted ignored
  $ echo "^ignored$" > .hgignore
  $ hg commit -A -m 'initial checkin'
  adding .hgignore
  adding deleted
  adding modified
  adding removed
  $ touch added unknown ignored
  $ hg add added
  $ echo "test" >> modified
  $ hg remove removed
  $ rm deleted
  $ hg copy modified copied

test unknown color

  $ hg --config color.status.modified=periwinkle status
  ignoring unknown color/effect 'periwinkle' (configured in color.status.modified)
  ignoring unknown color/effect 'periwinkle' (configured in color.status.modified)
  ignoring unknown color/effect 'periwinkle' (configured in color.status.modified)
  M modified
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1madded\x1b[0m (esc)
  \x1b[0;32;1mA \x1b[0m\x1b[0;32;1mcopied\x1b[0m (esc)
  \x1b[0;31;1mR \x1b[0m\x1b[0;31;1mremoved\x1b[0m (esc)
  \x1b[0;36;1;4m! \x1b[0m\x1b[0;36;1;4mdeleted\x1b[0m (esc)
  \x1b[0;35;1;4m? \x1b[0m\x1b[0;35;1;4munknown\x1b[0m (esc)

Run status with 2 different flags.
Check if result is the same or different.
If result is not as expected, raise error

  $ assert() {
  >     hg status $1 > ../a
  >     hg status $2 > ../b
  >     if diff ../a ../b > /dev/null; then
  >         out=0
  >     else
  >         out=1
  >     fi
  >     if [ $3 -eq 0 ]; then
  >         df="same"
  >     else
  >         df="different"
  >     fi
  >     if [ $out -ne $3 ]; then
  >         echo "Error on $1 and $2, should be $df."
  >     fi
  > }

assert flag1 flag2 [0-same | 1-different]

  $ assert "-q" "-mard"      0
  $ assert "-A" "-marduicC"  0
  $ assert "-qA" "-mardcC"   0
  $ assert "-qAui" "-A"      0
  $ assert "-qAu" "-marducC" 0
  $ assert "-qAi" "-mardicC" 0
  $ assert "-qu" "-u"        0
  $ assert "-q" "-u"         1
  $ assert "-m" "-a"         1
  $ assert "-r" "-d"         1
  $ cd ..

test 'resolve -l'

  $ hg init repo4
  $ cd repo4
  $ echo "file a" > a
  $ echo "file b" > b
  $ hg add a b
  $ hg commit -m "initial"
  $ echo "file a change 1" > a
  $ echo "file b change 1" > b
  $ hg commit -m "head 1"
  $ hg update 0
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "file a change 2" > a
  $ echo "file b change 2" > b
  $ hg commit -m "head 2"
  created new head
  $ hg merge
  merging a
  merging b
  warning: conflicts while merging a! (edit, then use 'hg resolve --mark')
  warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
  0 files updated, 0 files merged, 0 files removed, 2 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
  [1]
  $ hg resolve -m b

hg resolve with one unresolved, one resolved:

  $ hg resolve -l
  \x1b[0;31;1mU \x1b[0m\x1b[0;31;1ma\x1b[0m (esc)
  \x1b[0;32;1mR \x1b[0m\x1b[0;32;1mb\x1b[0m (esc)

color coding of error message with current availability of curses

  $ hg unknowncommand > /dev/null
  hg: unknown command 'unknowncommand'
  [255]

color coding of error message without curses

  $ echo 'raise ImportError' > curses.py
  $ PYTHONPATH=`pwd`:$PYTHONPATH hg unknowncommand > /dev/null
  hg: unknown command 'unknowncommand'
  [255]

  $ cd ..