For completeness, a few more lines from IRC:

13:56 < hreitz> Errr s/E2BIG/ENOSPC/
13:57 < kwolf> Anthony added it like this in 71d0770c4ce, and then we only had extensions and refactorings
13:58 < kwolf> Yes, ENOSPC actually has a different meaning because of the werror/rerror stuff
13:58 < kwolf> Well, only werror for ENOSPC