[TYPO3-core] why did jenkins reject my commit?

[Roland]

> So how would new contributers find out what is wrong with their patch the
> commit to Gerrit? IMHO this needs to be documented somewhere.
> To keep the motivation of the new contributers the same as before
> pushing it to Gerrit:-)

i would like to have a some more detailed guide what and how to test before
i push a commit. is there something in the wiki? the contribution
walkthrougguide does not tell anything about it. nobody wants to break
something. maybe some of the TDD12 sessions would have been helpful. i
could not attend. unfortunatelly they were not recorded. maybe this would
have been helpful?

ps: how safe is the jenkins safety net?