Per this question on SO, unless we can find some sort of standard that matches up with # GMT0BST,3,0,30,3600,10,0,26,7200[,3600], I think we can go ahead and deprecate it as a supported tzstr format (just in time now that @pablogsal has fixed it our support for it)!

I'm thinking we should

• Add a DeprecatedFormatWarning on a successfully parsed string in this format (not a DeprecationWarning, I want people to actually see it)
• Change all tests using this format so that they now check to make sure the warning is raised.
• Remove this format from all tests where we're not explicitly testing our support for the format.
• Remove any code examples or documentation related to this format, except possibly a .. caution note about the deprecation of the format.

I'm fairly confident that this won't cause major problems, since support for this format was inadvertently broken several releases back and we haven't heard anything.