Makes check script skip fetching LFS objects.
Makes check script skip fetching LFS objects.

Git LFS has recently been integrated into git more directly, so fetching
LFS objects now happens automatically without any special action, which
means that the 'check' script has begun fetching (possibly very large)
LFS objects during its initial clone and each time it finds a new commit.

In our check script, we don't ever need any LFS objects;  we're only
looking for commits.  So to avoid downloading those LFS objects, we set
an environment variable before cloning or fetching files.

Signed-off-by: Trevor Powell <064deff2c110d69624a1749813afa7492d8667d5@vectorstorm.org>

concourse/git-resource