Fix CI: Don't add & fetch remote if source branch == target branch

[kaxil]

CI has been failing on Master since last 2 days after #9922 was merged that added set -e which causes CI job to fail immediately if anything in that script fails.

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[potiuk]

Nice one @kaxil !

[kaxil]

:( it didn't fix it though - needs more debugging. Will look at it tomorrow if someone doesn't get to it first

[houqp]

my bad, thanks @kaxil and @zikun for taking care of it

[potiuk]

No worries QP: It's not an easy one to deal with the mutlttude of ways PR can be run :). And GitHub does not make it easy either. And the bad thing is that it's not easy to test how it will behave after you merge it to master I thin @zikun nicely shown all the different cases you might have when you try to interact/pull/push another branch:

PR: user:nonmaster -> apache:master
PR: user:master -> apache:master
PR: user:nonmaster -> user:master
PR: apache:nonmaster -> apache:master
CI build: apache:master

I'd also say that we have another one: scheduled nightly build (but this is a special cases for the last one "CI build".

And this is not even touching the case where we have v1-10-test and v1-10-stable branches involved - then it gets really messy as we can also have PRs towards v1-10-stable and direct pushes to v1-10-test. And sometimes we have PRs for v1-10-test 🤕

Luckily witth to openapi we are only concerned about master :).

One thing that I found useful though is that I have my own fork, and we have "PolideaInternal" fork for our organization so I try to reproduce the cases sometimes by pushing my branch as master to my own fork: git push -f potiuk MYBRANCH:master to simulate merge/scheduled push. That helps a bit (and I discussed yesterday similar strategy with Apache Beam team - I am consulting CI builds for them and they have very similar kinds of problems)

[kaxil]

Thanks @zikun @potiuk