When using JGit on a non-bare repository, the CloneCommand
it previously created local reflogs for all branches including remote
tracking ones, causing the generation of a potentially large
number of files on the local filesystem.
The creation of the remote-tracking branches (refs/remotes/*) during
clone is not an issue for the local filesystem because all of them are
stored in a single packed-refs file. However, the creation of a large
number of ref logs on a local filesystem IS an issue because it
may not be tuned or initialised in term of inodes to contain a very
large number of files.
When a user (or a CI system) performs the CloneCommand against
a potentially large repository (e.g., millions of branches), it is
interested in working or validating a single branch or tag and is
unlikely to work with all the remote-tracking branches.
The eager creation of a reflogs for all the remote-tracking branches is
not just a performance issue but may also compromise the ability to
use JGit for cloning a large repository.
The behaviour implemented in this change is also consistent with the
optimisation done in the C code-base [1].
We differentiate between clone and fetch commands using --branch
<initialBranch> option, that is only available in clone command,
and is set as HEAD per default.
[1] 58f233ce1e
Bug: 579805
Change-Id: I58d0d36a8a4ce42e0f59b8bf063747c4b81bd859
Signed-off-by: Luca Milanesio <luca.milanesio@gmail.com>
4bb4693633