Building ghc with "make -jN" gives different base ABI hashes for N<=8 and N>8
While building ghc-7.8.4 for Fedora 22 (devel) I found that doing highly parallel make builds of ghc affects the ABI hash of base, etc.
The threshold seems to be between -j8 and -j12, which likely changes the build order of some modules causing changes to ABI hashes.
While it is not hard to workaround, it is not really nice so it would be good to track this down IMHO. I haven't seen this kind of issue since 7.4.2 anyway so it may be an indirect buildsystem "regression" with ghc-7.8?