Bumps [bom-2.138.x](https://github.com/jenkinsci/bom) from 3 to 4.
- [Release notes](https://github.com/jenkinsci/bom/releases)
- [Commits](https://github.com/jenkinsci/bom/commits)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Not a healthy test because it depends on the names 
of branches on the remote repository.  Branch names
on the remote repository are now supplemented by
names from Dependabot and thus may be interesting
variants that will confuse this test.

Time to complete the task I set myself long ago of
completely replacing GitAPITestCase (a JUnit 3 test)
with the JUnit 4 equivalents that have already been 
started elsewhere in the repository

Same message as prior commit still applies.

This test is a good test of corner cases, but
it relies on state that is external to the test env.

See prior commit