Commit ac2e2c329145fe83037f8081018e502a953ab50d removed =gentoo-sources-4.1.15-r1, which is/was latest stable on amd64. Please restore the affected ebuild or mark a newer version stable.
Same happened here, gentoo-sources-4.1.12 was now emerged as "latest" stable version (with 4.1.15-r1 being latest stable installed before).
I'm sure it was a mistake. Will be restored soon.
*** Bug 577832 has been marked as a duplicate of this bug. ***
Restored by commit 846f5aa623679e960fee7b296b01dd8d9dbbef0f.