tests/test-narrow-clone-non-narrow-server.t

patch: make extract() a context manager (API)

Previously, this function was creating a temporary file and relying
on callers to unlink it. Yuck.

We convert the function to a context manager and tie the lifetime of
the temporary file to that of the context manager. This changed
indentation not only from the context manager, but also from the
elination of try blocks. It was just easier to split the heart of
extract() into its own function.

The single consumer of this function has been refactored to use it as
a context manager. Code for cleaning up the file in tryimportone()
has also been removed.

.. api::

   ``patch.extract()`` is now a context manager. Callers no longer have
   to worry about deleting the temporary file it creates, as the file is
   tied to the lifetime of the context manager.

Differential Revision: https://phab.mercurial-scm.org/D3306

Test attempting a narrow clone against a server that doesn't support narrowhg.

  $ . "$TESTDIR/narrow-library.sh"

  $ hg init master
  $ cd master

  $ for x in `$TESTDIR/seq.py 10`; do
  >   echo $x > "f$x"
  >   hg add "f$x"
  >   hg commit -m "Add $x"
  > done

  $ hg serve -a localhost -p $HGPORT1 --config extensions.narrow=! -d \
  >    --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"
  $ hg serve -a localhost -p $HGPORT2 -d --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"

Verify that narrow is advertised in the bundle2 capabilities:
  $ echo hello | hg -R . serve --stdio | \
  >   $PYTHON -c "from __future__ import print_function; import sys, urllib; print(urllib.unquote_plus(list(sys.stdin)[1]))" | grep narrow
  narrow=v0

  $ cd ..

  $ hg clone --narrow --include f1 http://localhost:$HGPORT1/ narrowclone
  requesting all changes
  abort: server doesn't support narrow clones
  [255]

Make a narrow clone (via HGPORT2), then try to narrow and widen
into it (from HGPORT1) to prove that narrowing is fine and widening fails
gracefully:
  $ hg clone -r 0 --narrow --include f1 http://localhost:$HGPORT2/ narrowclone
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets * (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrowclone
  $ hg tracked --addexclude f2 http://localhost:$HGPORT1/
  comparing with http://localhost:$HGPORT1/
  searching for changes
  looking for local changes to affected paths
  $ hg tracked --addinclude f1 http://localhost:$HGPORT1/
  comparing with http://localhost:$HGPORT1/
  searching for changes
  no changes found
  abort: server doesn't support narrow clones
  [255]