The bug seems to only effect Snow Leopard installations that use Bazaar and ProjectPlus within TextMate. It does not seem to be a Textmate problem.
In Snow Leopard switching off the Bazaar support in the preferences -> Project+ fixes the problem. (This tab is there only if ProjectPlus is installed).
With Bazaar support off Textmate will work properly. This is the case even if you have upgraded to the latest Bazaar for Snow Leopard.