Gentoo emerge: "Digest verification failed"

Params:
Linux moon 2.6.39-gentoo-r3 #4 SMP Wed Aug 31 17:44:51 EEST 2011 i686 AMD Athlon(tm) XP 2000+ AuthenticAMD GNU/Linux


Problem:
I have this error when trying emerge some applications

Calculating dependencies |  * Digest verification failed:
 * /usr/portage/dev-python/pygobject/pygobject-2.28.6.ebuild
 * Reason: Filesize does not match recorded size
 * Got: 3824
 * Expected: 3826
... done!


Solution:
> emerge --sync
> ebuild /usr/portage/dev-python/pygobject/pygobject-2.28.6.ebuild digest
> emerge --sync


But if you have a bulk of this warning, or you have also this warning:
A file is not listed in the Manifest '<package_ebuild>'
Then read this solution http://uommo.blogspot.com/2011/12/gentoo-emerge-file-is-not-listed-in.html