Change instructions for installing mysql ruby bindings.

+1 for changing the message to not point to the bad gem.

+1

So in the meantime the gem was updated on rubygems and looks to be maintained again.

I think this issue is resolved now:

Users without any mysql extension installed need an easy to follow instruction how to install mysql support:
This happens only when no mysql gem is available, right? So there's no version missmatch.

I really don't see your "can have only one binding installed at the same time" issue here.
Sure, it's a limitation but it's not relevant when the message is shown because no mysql extension is installed at all?

Or am I wrong?

Besides that: What if the tmtm.org site goes down? It's a single point of failiure and a maintenance mess to care about external URLs imho.

-1

Yes, the fact there there is a good very of the gem mostly resolves this issue.

Using gems to install binary bindings is still not a good idea because even though you are requiring one version of the gem, you may actually be getting another. This could be a very bad thing in a shared environment (you could end up using a bad version of the library even though you are requiring the correct one). This is somewhat mitigated by the fact that the mysql gem isn't updated very often.

Everybody else seems to be ok with installing binary libraries through gems, so I'm willing to throw up my arms on this one. Telling users to use the gem is certainly the easiest thing for them, even though it may not be the correct thing. Explaining the issue to new users would be nice, but it would probably just confuse most of them.

I guess the ideal solution would be to fix the mysql gem such that it does a check on activation to make sure the required gem version matches the library version that actually got loaded and throw an error if they do not match.