tests/helpers-testrepo.sh

merge: use operation-provided labels (ex: dest/source) in several merge-tools

Tools that did not use labels already, used only one, or used some label other
than the exact strings of "local" or "other" were unmodified.  Cases that used
the label "base" were modified as well, if they were otherwise changed in this
CL; "merged" was *not* changed.

There are other possible changes we might want to make, but I didn't:
- bcompare (linux and osx) uses the labels "parent1" and "parent2" instead of
  "local" and "other", so it was left alone, even though beyondcompare3
  (windows) *was* changed.
- araxis used the labels "Other", "Base", and "Local :$local", so it was also
  left alone.
- UltraCompare didn't provide a label for 'local', just for 'base' and 'other',
  so it was left alone.

Differential Revision: https://phab.mercurial-scm.org/D2012

# In most cases, the mercurial repository can be read by the bundled hg, but
# that isn't always true because third-party extensions may change the store
# format, for example. In which case, the system hg installation is used.
#
# We want to use the hg version being tested when interacting with the test
# repository, and the system hg when interacting with the mercurial source code
# repository.
#
# The mercurial source repository was typically orignally cloned with the
# system mercurial installation, and may require extensions or settings from
# the system installation.
syshg () {
    (
        syshgenv
        exec hg "$@"
    )
}

# Revert the environment so that running "hg" runs the system hg
# rather than the test hg installation.
syshgenv () {
    . "$HGTEST_RESTOREENV"
    HGPLAIN=1
    export HGPLAIN
}

# The test-repo is a live hg repository which may have evolution markers
# created, e.g. when a ~/.hgrc enabled evolution.
#
# Tests may be run using a custom HGRCPATH, which do not enable evolution
# markers by default.
#
# If test-repo includes evolution markers, and we do not enable evolution
# markers, hg will occasionally complain when it notices them, which disrupts
# tests resulting in sporadic failures.
#
# Since we aren't performing any write operations on the test-repo, there's
# no harm in telling hg that we support evolution markers, which is what the
# following lines for the hgrc file do:
cat >> "$HGRCPATH" << EOF
[experimental]
evolution = createmarkers
EOF

# Use the system hg command if the bundled hg can't read the repository with
# no warning nor error.
if [ -n "`hg id -R "$TESTDIR/.." 2>&1 >/dev/null`" ]; then
    alias testrepohg=syshg
    alias testrepohgenv=syshgenv
else
    alias testrepohg=hg
    alias testrepohgenv=:
fi