Fix mypy warning about short_help using __doc__

[thopre]

Summary

Several click.command use doc for the short_help but mypy is getting
confused because its type is a union between str and unicode due to
changes between Python2 and Python3. This commit clarifies to Mypy that
it is a string by calling str on doc.

[danilaml]

LGTM

lnt/tests/compile.py

def run_test(self, opts):
         server_report = self.submit(lnt_report_path, opts, ts_name='compile')
 
         return server_report
 
 
 # FIXME: an equivalent to argparse's add_argument_group is not implemented
 #        on click. Need to review it when such functionality is available.
 #        https://github.com/pallets/click/issues/373
[e-mail]("compile", help=usage_info, short_help=__doc__)
[e-mail]("compile", help=usage_info, short_help=str(__doc__))
 @click.argument("label", default=platform.uname()[1], required=False,
                 type=click.UNPROCESSED)
 @click.option("-s", "--sandbox", "sandbox_path", required=True,
               help="Parent directory to build and run tests in",
               type=click.UNPROCESSED, default=None, metavar="PATH")
 #  Test Options
 @click.option("--no-timestamp", "timestamp_build",
               help="Don't timestamp build directory (for testing)",

lnt/tests/nt.py

def _tools_check():
     status = call(["which", "tclsh"], stdout=FNULL, stderr=FNULL)
     if status > 0:
         raise SystemExit("""error: tclsh not available on your system.""")
 
 
 # FIXME: an equivalent to argparse's add_argument_group is not implemented
 #        on click. Need to review it when such functionality is available.
 #        https://github.com/pallets/click/issues/373
[e-mail]("nt", help=usage_info, short_help=__doc__)
[e-mail]("nt", help=usage_info, short_help=str(__doc__))
 @click.argument("label", default=platform.uname()[1], required=False,
                 type=click.UNPROCESSED)
 #  Sandbox
 @click.option("-s", "--sandbox", "sandbox_path", required=True,
               help="parent directory to build and run tests in",
               type=click.UNPROCESSED)
 @click.option("--no-timestamp", "timestamp_build", flag_value=False,
               default=True, show_default=True,

lnt/tests/test_suite.py

def diagnose(self):
         else:
             logger.warning("Skipping execution profiling because " +
                            "this is not Darwin.")
         logger.info("Report produced in: " + report_path)
 
         return lnt.util.ImportData.no_submit()
 
 
[e-mail]("test-suite", short_help=__doc__)
[e-mail]("test-suite", short_help=str(__doc__))
 @click.argument("label", default=platform.uname()[1], required=False,
                 type=click.UNPROCESSED)
 # Sandbox options
 @click.option("-S", "--sandbox", "sandbox_path", required=True,
               help="Parent directory to build and run tests in",
               type=click.UNPROCESSED, metavar="PATH")
 @click.option("--no-timestamp", "timestamp_build",
               flag_value=False, default=True,