darcs2hg.py: import darcs project into mercurial
For now, the tags are not taken into account (so you have to reenter
the tags by hand)
abort: repository a not found!
255
abort: error: Connection refused
255
abort: repository a not found!
255
abort: destination '../a' already exists
255
abort: repository a not found!
255
abort: destination 'q' already exists