tests/test-merge-symlinks

verify: fix "missing revlog!" errors for revlog format v0 and add test

With revlog format v0 the .d files are empty if the only revision stored is an
empty file. Since Mercurial can no longer create format v0 repositories, but
still use it, add a script which creates a repository with a single empty file.
This can be used in other tests if wanted.

#!/bin/sh

cat > echo.py <<EOF
#!/usr/bin/env python
import os, sys
try:
    import msvcrt
    msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
    msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
    pass

for k in ('HG_FILE', 'HG_MY_ISLINK', 'HG_OTHER_ISLINK', 'HG_BASE_ISLINK'):
    print k, os.environ[k]
EOF

# Create 2 heads containing the same file, once as
# a file, once as a link. Bundle was generated with:
#
# hg init t
# cd t
# echo a > a
# hg ci -qAm t0 -d '0 0'
# echo l > l
# hg ci -qAm t1 -d '1 0'
# hg up -C 0
# ln -s a l
# hg ci -qAm t2 -d '2 0'
# echo l2 > l2
# hg ci -qAm t3 -d '3 0'

hg init t
cd t
hg -q pull "$TESTDIR/test-merge-symlinks.hg"
hg up -C 3

# Merge them and display *_ISLINK vars
echo % merge heads
HGMERGE="python ../echo.py" hg merge

# Test working directory symlink bit calculation wrt copies,
# especially on non-supporting systems.
echo % merge working directory
hg up -C 2
hg copy l l2
HGMERGE="python ../echo.py" hg up 3