Merging unrelated repositories

As I start up with git, I am also starting up work with several codebases that I am unfamiliar with.

The codebases are mostly under SVN, but not all; some are under CVS, some Perforce. I have decided to just suck everything into git for purposes of tracking any changes I am making myself. I am not linking to svn repos or anything else; I am just sucking in the SVN and CVS metadata, with the expectation that I can work under git, and then do a svn checkin.

The codebases are structured as overlapping projects, subprojects, and libraries. I was not aware of the relationship between the subprojects and libraries. E.g. I checked out a library, placed it under git, made changes - and now have checked out another tool that has this library as a subcomponent. I want the new tool to lie in git as well, and I want to checkin the vanilla source code - but I also, eventually, want to use my edits to the library with the new tool.

Basically, I am doing a lot of work with subprojects. I am doing a lot of work with initially unrelated repositories.


Here's a link to a procedure on "Merging two unrelated repositories":
http://www.simplicidade.org/notes/archives/2009/04/merging_two_unr.html