Fix handling of paths when run outside the repo. The main problem was that dirstate.getcwd() returned just "", which was interpreted as "we're at the repo root". It now returns an absolute path. The util.pathto function was also changed to deal with the "cwd is an absolute path" case.

adding he
llo
abort: '\n' and '\r' disallowed in filenames
adding he
llo
abort: '\n' and '\r' disallowed in filenames
hell
o
nothing changed