docs: def get_vr(self, epoch=None):
          """get VR string from .spec Version, Release and Epoch
  
          epoch is None: prefix epoch if present (default)
          epoch is True: prefix epoch even if not present (0:)
          epoch is False: omit epoch even if present
          """
          version = self.get_tag('Version', expand_macros=True)
          e = None
          if epoch is None or epoch:
              try:
                  e = self.get_tag('Epoch')
              except exception.SpecFileParseError:
                  pass
          if epoch is None and e:
              epoch = True
          if epoch:
              if not e:
                  e = '0'
              version = '%s:%s' % (e, version)
          release = self.get_tag('Release')
          release = re.sub(r'%\{?\??dist\}?$', '', release)
          release = self.expand_macro(release)
          if release:
              return '%s-%s' % (version, release)
          return version