tests/test-grep

convert: fix mercurial_sink.putcommit

Changeset 4ebc8693ce72 added some code to putcommit to avoid creating a
revision that touches no files, but this can break regular conversions
from some repositories:

- conceptually, since we're converting a repo, we should try to make
  the new hg repo as similar as possible to the original repo - we
  should create a new changeset, even if the original revision didn't
  touch any files (maybe the commit message had some important bit);

- even if a "regular" revision that doesn't touch any file may seem
  weird (and maybe even broken), it's completely legitimate for a merge
  revision to not touch any file, and, if we just skip it, the
  converted repo will end up with wrong history and possibly an extra
  head.

  As an example, say the crew and main hg repos are sync'ed.  Somebody
  sends an important patch to the mailing list.  Matt quickly applies
  and pushes it.  But at the same time somebody also applies it to crew
  and pushes it.  Suppose the commit message ended up being a bit
  different (say, there was a typo and somebody didn't fix it) or that
  the date ended up being different (because of different patch-applying
  scripts): the changeset hashes will be different, but the manifests
  will be the same.

  Since both changesets were pushed to public repos, it's hard to recall
  them.  If both are merged, the manifest from the resulting merge
  revision will have the exact same contents as its parents - i.e. the
  merge revision really doesn't touch any file at all.

To keep the file filtering stuff "working", the generic code was changed
to skip empty revisions if we're filtering the repo, fixing a bug in the
process (we want parents[0] instead of tip).

#!/bin/sh

mkdir t
cd t
hg init
echo import > port
hg add port
hg commit -m 0 -u spam -d '0 0'
echo export >> port
hg commit -m 1 -u eggs -d '1 0'
echo export > port
echo vaportight >> port
echo 'import/export' >> port
hg commit -m 2 -u spam -d '2 0'
echo 'import/export' >> port
hg commit -m 3 -u eggs -d '3 0'
head -n 3 port > port1
mv port1 port
hg commit -m 4 -u spam -d '4 0'
echo % pattern error
hg grep '**test**'
echo % simple
hg grep port port
echo % all
hg grep --all -nu port port
echo % other
hg grep import port

hg cp port port2
hg commit -m 4 -u spam -d '5 0'
echo '% follow'
hg grep -f 'import$' port2
echo deport >> port2
hg commit -m 5 -u eggs -d '6 0'
hg grep -f --all -nu port port2

cd ..
hg init t2
cd t2
hg grep foobar foo
hg grep foobar
echo blue >> color
echo black >> color
hg add color
hg ci -m 0 -d '0 0'
echo orange >> color
hg ci -m 1 -d '0 0'
echo black > color
hg ci -m 2 -d '0 0'
echo orange >> color
echo blue >> color
hg ci -m 3 -d '0 0'
hg grep orange
hg grep --all orange

# Got a traceback when using grep on a single
# revision with renamed files.
cd ..
echo % issue 685
hg init issue685
cd issue685
echo octarine > color
hg ci -Amcolor
hg rename color colour
hg ci -Am rename
hg grep octarine
# Used to crash here
hg grep -r 1 octarine