Push failures drop some of git's error explanations

[Robie Basak]

"git push <local annotated tag name>:refs/heads/<new branch name>" fails because the remote git will not accept an annotated tag as a commit object that a branch can point to. For example:

$ git push localhost:/tmp/foo refs/tags/2.11-1ubuntu1:refs/heads/ubuntu/devel
Authenticated with partial success.
Verification code:
Password:
Counting objects: 50, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (41/41), done.
Writing objects: 100% (50/50), 65.26 KiB | 0 bytes/s, done.
Total 50 (delta 4), reused 0 (delta 0)
error: Trying to write non-commit object 8bd94ee19a36c6e1fae755a8a572150b442b0e54 to branch refs/heads/ubuntu/devel
remote: error: cannot update the ref 'refs/heads/ubuntu/devel'.
To localhost:/tmp/foo
 ! [remote rejected] 2.11-1ubuntu1 -> ubuntu/devel (failed to update ref)
error: failed to push some refs to 'localhost:/tmp/foo'

While I would like git to dtrt here, that is a git (perhaps wishlist) bug and not a bug in turnip.

However, when I do the same thing to Launchpad, I do not see the "error: Trying to write to non-commit object ..." message, making it difficult to understand what is wrong. The message I see is the same as above, except that single line "error: Trying to write..." is missing. For example:

$ git push lp:~racb/ubuntu/+source/ntp 1_4.2.6.p5+dfsg-3ubuntu9:refs/heads/ubuntu/devel
Counting objects: 45, done.
Delta compression using up to 4 threads.
Compressing objects: 100% (45/45), done.
Writing objects: 100% (45/45), 37.35 KiB | 0 bytes/s, done.
Total 45 (delta 13), reused 0 (delta 0)
To git+ssh://<email address hidden>/~racb/ubuntu/+source/ntp
 ! [remote rejected] 1_4.2.6.p5+dfsg-3ubuntu9 -> ubuntu/devel (failed to write)
error: failed to push some refs to 'git+ssh://<email address hidden>/~racb/ubuntu/+source/ntp'

So: expected result: "error: Trying to write..." message; actual result: all of the same text except for that line.

[William Grant (wgrant)]

This is actually down the version of git on the server. It'll be fixed when production is upgraded to xenial.