gen_makefile: fix empty push-url for 'make regen'
diff --git a/gen_makefile.py b/gen_makefile.py
index 8321fb8..cfe3180 100755
--- a/gen_makefile.py
+++ b/gen_makefile.py
@@ -81,7 +81,7 @@
port 29418
you may pass '-u ssh://go' to be able to submit to gerrit.''')
-parser.add_argument('-p', '--push-url', dest='push_url', default=None,
+parser.add_argument('-p', '--push-url', dest='push_url', default='',
help='''git push-URL. Default is to not configure a separate push-URL.''')
parser.add_argument('-o', '--output', dest='output', default='Makefile',