test-merge-tool: Make sure no hgmerge can be found in $PATH
The merge tool selecting algorithm is hardcoded to look for hgmerge in $PATH
before it falls back to use internal merge. This fixes the test for this
fallback to be tolerant to existing hgmerges.
adding a
adding b
adding c
% should succeed
200 Script output follows
/al/
/b/
/c/
200 Script output follows
a
200 Script output follows
b
200 Script output follows
c
% should fail
404 Not Found
error: repository circle not found
404 Not Found
error: repository circle not found
404 Not Found
error: repository circle not found
% collections errors