Fix the way PR build clones gVisor.

Copybara force-pushes to the PR immediately before merging which triggers a PR
build. Since the PR is merged, the refspec +refs/pull/{pr_num}/merge is not
available and the build fails causing all master commit CI builds to show a
failure.

This change remove the clone step from travis and clone manually in a way
which always would succeed. We fetch +refs/pull/{pr_num}/head and cherry pick
that onto the target branch.

I have tested this in https://github.com/ayushr2/gvisor/pull/1 and
https://github.com/ayushr2/gvisor/pull/2.

PiperOrigin-RevId: 317759891

0 files changed, 0 insertions, 0 deletions