darcs2hg.py: use darcs patch hash as patch identifier The use of the patch name is dangerous when duplicate names exist. In case of a duplicate name the second patch and all its dependancies are merged into a single mercurial patch. The patch identifier (hash) is always unique.

# should print nothing
# should print ? b/x
? b/x
# should print A b/x
A b/x
# should forget b/x
forgetting b/x
# should print nothing