All right. The ultimate solution:

{{{
# Imports for converting version to MSI format for bdist_msi
from distutils.command.bdist_msi import bdist_msi
import inspect
import types
 
...

class bdist_msi_patch_version(bdist_msi):
    """ MSI builder requires version to be in the x.x.x format """
    def run(self):
        def monkey_get_version(self):
            """ monkey patch replacement for metadata.get_version() that
                returns MSI compatible version string for bdist_msi
            """
            # get filename of the calling function
            if inspect.stack()[1][1].endswith('bdist_msi.py'):
                # strip revision from version (if any), e.g. 11.0.0-r31546
                return self.version.split('-')[0]
            else:
                return self.version

        # monkeypatching get_version() call for DistributionMetadata
        self.distribution.metadata.get_version = \
            types.MethodType(monkey_get_version, self.distribution.metadata)
        bdist_msi.run(self)


...
setup(
    ...
    cmdclass={'bdist_msi': bdist_msi_version_hack},
)
}}}