commands: only pass --jobs to 'git clone' if set

[technoweenie]

Running git lfs clone always passes the --jobs option to git clone. This won't fly if you have git < 2.9:

error: unknown option `jobs'
usage: git clone [<options>] [--] <repo> [<dir>]

Fixes #2366 by setting the flag default to -1.

[ttaylorr]

Looks good, and thanks for getting to this. None of the other flags added in #2252 should be affected by this since they are all strings and len(str) > 0 is the inclusion check for those.

[technoweenie]

Ah, the reason our ci didn't catch this is because typically test against 3 git versions (on circle and travis):

• Latest release
• GIT_EARLIEST_SUPPORTED_VERSION which is 2.0.0.
• Current master branch.

The GIT_EARLIEST_SUPPORTED_VERSION test should have caught this, but the clone test requires git 2.2.0+. Doh. I don't know if it's worth adding to the test matrix though.

[ttaylorr]

The GIT_EARLIEST_SUPPORTED_VERSION test should have caught this, but the clone test requires git 2.2.0+. Doh. I don't know if it's worth adding to the test matrix though.

Ah, thanks for the explanation. This was very helpful. I think it's certainly worth poking around at to split out the tests that require Git 2.2.0+ and those that don't into separate test files. I don't have time to get to this immediately, but I've opened up #2391 to track this for the 2.3.0 release.