No they shouldn't, if avoidable. It's a problem that in my experience happens far too often. However I believe it is more to do with ignorance of how to use git correctly than somebody wanting to steal credit.

• If they want to modify your change before applying it to their main branch they can easily create a branch for your change where they add their own commit after yours and then merge the branch in.
• If your pull request is not based on the latest version of their main branch then they can issue a git rebase master. If there are conflicts they can either choose to fix the conflicts themselves (without changing author) or give you the chance to fix it.

I think Github could and should look for this kind of accidental credit stealing and educate maintainers on best practices when appropriate.

No they shouldn't, if avoidable. It's a problem that in my experience happens far too often. However I believe it is more to do with ignorance of how to use git correctly than somebody wanting to steal credit.

• If they want to modify your change before applying it to their main branch, they can easily create a branch for your change. They can then add their own commit after yours and then merge the branch in.
• If your pull request is not based on the latest version of their main branch, then they can issue a git rebase master. If there are conflicts they can either choose to fix the conflicts themselves (without changing author), or give you the chance to fix it.

I think Github could and should look for this kind of accidental credit stealing and educate maintainers on best practices when appropriate.