tests/test-check-code-hg.t

revert: extract actual revert in its own function

With this small refactoring, the computation of the action to perform and the
actual change to the disk happen in different function. This allows extension to
wrap the later in case of need. The initial motivation is the `remotefilelog`
extension that need to prefetch all the file content to be checked out.

  $ check_code="$TESTDIR"/../contrib/check-code.py
  $ cd "$TESTDIR"/..
  $ if hg identify -q > /dev/null 2>&1; then :
  > else
  >     echo "skipped: not a Mercurial working dir" >&2
  >     exit 80
  > fi

Prepare check for Python files without py extension

  $ cp \
  >   hg \
  >   hgweb.cgi \
  >   contrib/convert-repo \
  >   contrib/dumprevlog \
  >   contrib/hgweb.fcgi \
  >   contrib/hgweb.wsgi \
  >   contrib/simplemerge \
  >   contrib/undumprevlog \
  >   i18n/hggettext \
  >   i18n/posplit \
  >   tests/hghave \
  >   tests/dummyssh \
  >   "$TESTTMP"/
  $ for f in "$TESTTMP"/*; do mv "$f" "$f.py"; done

New errors are not allowed. Warnings are strongly discouraged.
(The writing "no-che?k-code" is for not skipping this file when checking.)

  $ { hg manifest 2>/dev/null; ls "$TESTTMP"/*.py | sed 's-\\-/-g'; } |
  >   xargs "$check_code" --warnings --per-file=0 || false
  Skipping hgext/zeroconf/Zeroconf.py it has no-che?k-code (glob)
  Skipping i18n/polib.py it has no-che?k-code (glob)
  Skipping mercurial/httpclient/__init__.py it has no-che?k-code (glob)
  Skipping mercurial/httpclient/_readers.py it has no-che?k-code (glob)
  Skipping mercurial/httpclient/socketutil.py it has no-che?k-code (glob)