[OE-core] Can we trust to sstate-cache?

[Marcin Juszkiewicz]

Today I bumped gcc-linaro from 4.7-r5 to 4.7-r6. First version was plain
2012.10 release while second one was tarball from bzr repository with
huge set of ICE related fixes for AArch64 architecture.

To do fast clean build I removed TMPDIR and started new build of
core-image-minimal target.

But then I noticed ugly thing:

0: eglibc-2.16-r18+svnr20393 do_populate_sysroot_setscene (pid 30106)
1: eglibc-2.16-r18+svnr20393 do_package_setscene (pid 30107)
3: eglibc-initial-2.16-r18+svnr20393 do_package_setscene (pid 28921)

Why eglibc was taken from sstate-cache instead of being rebuilt (like it
was with 'db')? This makes me sad as it shows that I cannot trust
sstate-cache so each new build will take hours instead of minutes.

Or maybe I am wrong?