run-tests: redefine --with-hg so it takes the 'hg' script to run. - in parseargs(), check that --with-hg value is valid - add handy --local option for "--with-hg=../hg" - ensure that we always set PATH and PYTHONPATH (not just when doing a temporary install) - override any existing PYTHONPATH, so test success does not depend on whatever happens to be in the caller's environment - give tests a little more control by exporting $PYTHON to the environment; needed by test-convert and test-mergetool when they run hg with a stripped-down $PATH Also, add a big comment explaining all the corner cases to test for the next person who tries to modify this script.

% should be empty
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
a
b/a
l
644   a
755 * b/a
644 @ l
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a
b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 755 * b/a
047b75c6d7a3ef6a2243bd0e99f94f6ea6683597 644 @ l
a
l
a
b/a
l
a
b/a
l
% should fail
abort: unknown revision '2'!
abort: please specify just one revision
a
b/a
l