Clean build on HEAD on Linux is now giving a new error. 

Actual stderr output differs from expected:

--- ./driver/T10970a.stderr.normalised    2015-10-27 09:44:02.279188078 +0000

+++ ./driver/T10970a.comp.stderr.normalised     2015-10-27 09:44:02.279188078 +0000

@@ -1,6 +1,4 @@

 T10970a.hs:4:0:

      missing binary operator before token "("

-     #if MIN_VERSION_base(3,0,0)

-     ^

`gcc' failed in phase `C pre-processor'. (Exit code: 1)

I figured out the recomp013 problem; there was a commit which interacted badly with link trees

commit cdca31ebf7744dcae66a6715500395a63bcc3ee2

Author: Edward Z. Yang <ezyang@cs.stanford.edu>

Date:   Wed Sep 9 22:02:48 2015 -0700

    Don't check in autogenerated hs files for recomp013..