Github has magic refs called pull/NN/head, pull/NN/merge.
I want to understand what's keeping something like this from working:
$ git clone https://github.com/cben/sandbox --branch pull/7/merge
Cloning into 'sandbox'...
fatal: Remote branch pull/7/merge not found in upstream origin
This is probably because these refs are neither under refs/branches nor refs/tags (git clone --branch docs say it can also take a tag):
$ git ls-remote https://github.com/cben/sandbox
71bea916dee6a03221443cc15c254edc97ff8d42 HEAD
e2f53347112b66ceba2986339c66244cd4458209 refs/heads/branch-to-remain-unmerged
71bea916dee6a03221443cc15c254edc97ff8d42 refs/heads/gh-pages
a34f5181eb779bb6728725f0b21fd9bc78c0d0a8 refs/heads/master
6a23126f508a59c006163aa7fee2dbb7b12d871e refs/heads/prefixed-header
8ce1ef94fa1e8bf0456aac5368edf0ccdf2c2f3a refs/heads/test-push-from-c9
6a23126f508a59c006163aa7fee2dbb7b12d871e refs/pull/6/head
e2f53347112b66ceba2986339c66244cd4458209 refs/pull/7/head
a18487b006434d4f83a6738c1031a80d845bb303 refs/pull/7/merge
71bea916dee6a03221443cc15c254edc97ff8d42 refs/tags/a-tag
Is another way to make git clone checkout an arbitrary ref (preferably in --single-branch / --depth 1 mode)?
I know I could clone another branch/tag, fetch this ref and checkout FETCH_HEAD. I can even use empty git repo technique from https://stackoverflow.com/a/4146786/239657 to avoid downloading anything else:
$ git init
$ git remote add origin https://github.com/cben/sandbox
$ git fetch origin pull/7/merge --depth 1
$ git checkout --detach FETCH_HEAD
but my motivation is not just achieving the clone — it's figuring out if I can coax tools like npm and Bundler that accept git url branch into using a pull/NN/merge ref directly.
:ref => "refs/pull/232/merge"! It has special handling if ref starts with ref/ — an extra git fetch and later in same file reset --hard to the desired revision.