dev-libs/libgcrypt-1.5.4 was released on 2014-08-07.
Probably it would suffice to add it in slot "11" and not in slot "0".
@crypto, do we expect to stabilize 1.6* anytime soon, or would you prefer getting 1.5.4 stable instead? I don't see any security issues mentioned in the NEWS, just some minor bugs.
Michal, we do expect to stabilize 1.6, but I added this anyway.