test: make test runs robust against a non-"master" defaultBranch

[marcelltoth]

Summary

This is a tiny fix related to my contribution at #1270 .

When running the tests locally they were failing because my init.defaultBranch is set to main (was a requirement for some other work). Some of the tests make assumption about the branch name, and will fail if it's not master.

This tiny change makes the test runs more robust by specifying the initial branch name explicitly. This will also shield against any future changes in the default value of the property. This may very well happen, see git docs:

[okonet]

Can we change it to main instead?

[marcelltoth]

Can we change it to main instead?

We sure can, but that requires changing the tests that mention master to main. I can do that if you'd like me to. Should I?

[iiroj]

Sorry, this has become stale. A similar fix will be included in #1303 so closing this.

We can change everything from master to main at some point, but let's do it separately.