We should mask =sys-kernel/gentoo-sources-3.14.72 due to a serious problem introduced with commit c66edeaf79bb6f0ca688ffec9ca50a61b7569984 and now reverted in 3.14.73 via commit 032ac851fd42a62717032a594ac319f8a76b8a7d affecting people using XFS. For more details see $URL.
Not in the tree any more.