Contribution licensing question(s)

Hi,

My employer has a new-ish open-source-contribution process, and is curious about some licensing question(s) before I submit a few patch series.

Background: git's README.md file points out that some parts of git are
under a license other than GPLv2 (while still GPLv2-compatible),
though it doesn't state which one(s) or what a contributor might want
to do if they want to grant permission under one of those more
permissive license(s). Also, I seem to recall that years ago there
were requests to make code available under a slightly more permissive
license to allow re-usage in jgit and perhaps other projects, though I
can't find any trace of this in the codebase.  git's COPYING file has
wording suggesting how to make a license transition (to GPLv3) easier,
but only considers completely new files as opposed to (significant)
modifications to existing files.

I'm not sure whether my specific git contributions would matter to jgit (which we also use internally, both directly and indirectly), but generally, is contributing under a more permissive GPLv2-compatible license to permit re-usage in other projects like jgit (or for easing future license switches) still relevant? If so, which license(s) have folks gravitated towards for these contributions, and how would one mark their submitted patches?

Thanks, Elijah