jenkins/build-seed: clone or rebase openbmc

Previously the script would only clone the main openbmc
repository, which would cause it to fail if ran multiple
times.  Add logic to fetch/rebase when the repository
already exists.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic62a9fa320afab4e1a761fdf61d3e5b2d1a54232
1 file changed