fix traceback of extdiff after a merge
- files that comes from a different branch are marked as modified
but aren't present in the original manifest
- add a testcase for extdiff and for regular diff
syntax: glob
*.elc
*.orig
*.rej
*~
*.o
*.so
*.pyc
*.swp
*.prof
tests/.coverage*
tests/annotated
tests/*.err
build
contrib/hgsh/hgsh
dist
doc/*.[0-9]
doc/*.[0-9].gendoc.txt
doc/*.[0-9].{x,ht}ml
MANIFEST
patches
mercurial/__version__.py
.DS_Store
syntax: regexp
^\.pc/
Output/Mercurial-[0-9.]*.exe