Bridges should report implementation versions of their pluggable transports

Our bridges now run a variety of pluggable transports. What if there's a bug in, say, the Scramblesuit implementation (like it appears there is)? If we fix the bug, how do bridgedb or the Tor clients know whether the Scramblesuit bridge they just learned about is one of the new (updated) ones or one of the old (buggy) ones?

One option would be for Tor to include a version for each supported PT in its bridge (or extrainfo) descriptor, so if we turn out to not want to use certain versions for certain situations, we can do it.

Are there better options than this one?