Long-lived branches, linear history

Hey all,

I have a couple of long lived branches. Because I might want to upstream them at some point, I keep rebasing them to keep them compatible, as “rebasing” and “linear history” are part of the (unwritten?) requirements for PRs. That’s not very convenient, history gets weird in my branches because commit messages sometimes don’t make sense anymore on top of the rebase target, etc.

So, I was wondering, for large and long-lived branches, is it fine to merge branches (PRs) that have kept up-to-date with master by merging in master from time to time, Linux style?