from nss-3.11.1.ebuild lines 7 and 20 make a hard dependancy on nspr-4.6.2 but emerge =dev-libs/nspr-4.6.2* renders !!! All ebuilds that could satisfy "=dev-libs/nspr-4.6.2" have been masked. !!! One of the following masked packages is required to complete your request: - dev-libs/nspr-4.6.2 (masked by: ~x86 keyword) therefore nss-3.11.1 should be masked or nspr unmask
dev-libs/nss-3.11.1 is unstable, dev-libs/nspr-4.6.2 is unstable as well. Nothing package.masked. If you put some ebuild into package.keywords, you need to do the same for its dependencies. No bug here.
Ahh sorry when firefox 1.5 was masked I added nss and it compile (probably back then the corresponding nspr was not mask) so it compile right now I have taken both nss and firefox from my package.unmask you could have said it on irc :) although I didn't think you check it back then, sorry for the troubles.