Having read about the libc5 fork of glibc in Rick Moen's "Fear of Forking" essay, I went looking for more info about this fork since it seems to have healed so well that no one ever talks about it anymore. It also seems strangely underdocumented for a 10 year old event in a community that values putting everything about everything online.
http://fsfe.org/en/fellows/ciaran/ciaran_s_free_software_notes/history_of_gl...
If anyone knows any other sources of info that I didn't reference, I'd be happy to hear about them.