When initializing a workspace that shares its working copy with a Git
repo (i.e. `jj init --git-repo=.`), we import refs and HEAD when
creating the `WorkspaceCommandHelper` (as we do for all commands when
the working copy is shared). That makes the explicit import we do in
`cmd_init()` unnecessary. It also makes the checkout of HEAD I added
for the fix of #102 unnecessary. More importantly, as @yuja reported
in #177, it makes the command crash (at least if the repo is small
enough that the two checkouts happen within a second). I think the
problem is that the second checkout tries to create the same commit
except that the Change ID is different (the problem is not the
predecessors as I speculated in the issue tracker). The fix is to
simply avoid doing the redundant work. We still need a proper fix for
#27 eventually.
Closes#177.
This patch adds a very simple e2e test of having a working copy shared
with Git. The test initially failed on Windows. The symptom was that
the "master" branch did not get updated when we create a commit using
`jj`. That suggested that we didn't correctly detect that the working
copy was shared. After a lot of troubleshooting, I think I mostly
understand what we going on here (thanks to @arxanas for suggesting
https://github.com/mxschmitt/action-tmate). The path we get from
`git2::Repository::workdir()` seems to not be canonicalized in the
same way as `std::fs::canonicalize()` canonicalizes. Specifically, it
does not have the "\\?\" prefix we get from that function. I suppose
that's because libgit2 is a C library and canonicalizes the path using
some other system call.
