[TYPO3-core] how to contribute to "version", "workspaces", "extbase", "fluid", "dbal" and "linkvalidator"?

[Roland]

> Those git submodels are "real" independent repositories, so you can just cd 
> into the folder (e.g. typo3/sysext/linkvalidator), checkout the master, 
> pull, change and commit and finnally push to the repositorty.

i checked out an issue branch with "git checkout -b issue_xxxxx"

could this be a problem? do i have to leave this branch after pushing? to
which branch do i have to switch?

kind regards.

roland