Add hghave utility and run-tests.py support.
hghave detects system features like symlinks availability at run-time. Tests can be skipped by starting them with:
"$TESTDIR/hghave" symlink || exit 80
The 80 exit status triggers hghave output handling by run-tests.py. Also, tests output can be locally patched on the fly to match reference output.
#!/bin/sh
hg init
echo "Is there an error message when trying to diff non-existing files?"
hg diff not found
echo "Is there an error message when trying to add non-existing files?"
hg add not found