cloudtools/troposphere — pull request #75 by tigertoes (2014-04-29 16:09:35+00:00)
Title: MinInstancesInService can also be a Ref()

Validation will just skip if this is the case, however. This is more or less consistent with how other values do this (2779a2e22575744ea3bb69d7a70b11a15aaa8ecd for example).