exec used as a method breaks lib2to3

[DRMacIver]

Formatting the following crashes (under both 2.7.8 and 3.4.2):

methods.exec(sys.modules[name])

The error is:

lib2to3.pgen2.parse.ParseError: bad input: type=1, value='exec', context=('', (1, 8))

Running 2to3 on the same code produces the same parse error, so this is a limitation of the library.