run-tests: avoid set PYTHONUSERBASE environment variable to None
According to python documentation, get_config_var can return None and it was
during running mercurial tests under a virtual environment with the local built
mercurial installed as a python package with `pip install -e .`.
On the other hand, if mercurial is installed in the user library folders with
`pip install --local -e .` the issue doesn't reproduce.
The fallback is that it will just set an empty string and everything should work
as before, according to https://www.python.org/dev/peps/pep-0370/:
The path to the user base directory can be overwritten with the environment
variable PYTHONUSERBASE. The default location is used when PYTHONUSERBASE is
not set or empty.
--- a/tests/run-tests.py Sun Jan 07 12:07:29 2018 +0900
+++ b/tests/run-tests.py Mon Jan 08 13:52:43 2018 +0100
@@ -1021,7 +1021,7 @@
offset = '' if i == 0 else '%s' % i
env["HGPORT%s" % offset] = '%s' % (self._startport + i)
env = os.environ.copy()
- env['PYTHONUSERBASE'] = sysconfig.get_config_var('userbase')
+ env['PYTHONUSERBASE'] = sysconfig.get_config_var('userbase') or ''
env['HGEMITWARNINGS'] = '1'
env['TESTTMP'] = self._testtmp
env['HOME'] = self._testtmp