inotify: don't fall over just because of a dangling symlink
Previously, the inotify server failed to start if .hg/inotify.sock was
a symlink that pointed to a non-existent path. This behaviour does not
seem to make any sense.
Now, if we encounter a broken symlink, we unlink it and continue.
http://mercurial.selenic.com/bts/issue1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b (glob)
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..