convert: pass absolute paths to git (SEC)
Fixes CVE-2016-3105 (1/1).
Previously, it was possible for the repository path passed to git-ls-remote
to be misinterpreted as a URL.
Always passing an absolute path to git is a simple way to avoid this.
https://bz.mercurial-scm.org/1089
$ 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 ..