This is something that happened when we switched over to expandlibs, and that's again something that happens with bug 677501. This effectively requires a clobber, when we really prefer to avoid that.
Created attachment 557473 [details] [diff] [review] Remove stale static library when only creating a fakelib
The whole b-s merge backed out of m-c for causing bustage: http://hg.mozilla.org/mozilla-central/rev/472716252ea3 https://tbpl.mozilla.org/?usebuildbot=1&rev=e5815c156b6c
The backout was backed out