When I installed my new laptop, I wanted to have a browser "now". So I emerged mozilla-firebird-bin, which is ugly as sin, doesn't have GTK2 support, or a few other very nice things. so I emerged mozilla-firebird. Unfortunatly this is blocked by mozilla-firebird-bin, so I had to go to sleep while this was happening, because I didn't have a browser. I don't understand why mozilla-firebird-bin isn't REPLACED by mozilla-firebird rather than blocking it.
because if you update the source version and an update comes in on the -bin version, your wonderfully src-compiled binaries will be overwritten
The purpose of a blocker in portage is to indicate to the user that the existing package provides the same functionality, and should manually be replaced. Doing it automatically would surely cause unpredictable results for many users. To emerge one of the other variants, simply unmerge the blocker first.
And cannot be done with current portage functionality ...
