Some ancient source code given away freely by Sun in 1984 turned out to have a non-free-software license all these years, upsetting the licensing purity of glibc and everything built with it.
This may come as a shock, but all Gnu/Linux distributions to date have been built with essential software under a license that clearly meets neither the open source definition nor the Free Software Foundations' requirements for a free software license. The tenacity of a Red Hat hacker has finally solved this problem for everyone, however, and I'm proud to have played a part, too.
One of the long-running projects I had at Sun was to get the (pre-GPL, permissive) license on Sun RPC changed. Why would that interest anyone? Well, the code in question is the original implementation of Sun RPC, which went on to become RFC 1057 and today is a core part of every Unix-family operating system. Including Debian Gnu/Linux and Fedora, both keen to be 100-percent free-licensed software.
The way the RPC code was originally licensed was exceptionally liberal. Written in 1984 or earlier (well before the GPL existed), it allowed unfettered use of the Sun RPC implementation in any program for any purpose. The only significant restriction imposed, entirely reasonable to most eyes then, was to say that the module itself could not be sold as is, only as part of a larger work. The code was circulated on Usenet and was extensively cut and pasted into software being developed then -- notably the parts related to NFS.