boto/boto — pull request #972 by acrefoot (2012-09-07 18:17:44+00:00)
Title: Allow non-numerics in a RegExConstraint's attributes. Fixes issue #941.

https://github.com/boto/boto/issues/941

One cannot create RegExConstraints (with non-numeric regex strings) with the current scheme, as described in the issue. I've overridden the behavior in only RegExConstraints, as I believe all other constraints do take numeric attributes.