Use argparse.REMAINDER instead of action=append
This gathers up all the remaining parameters without misinterpreting
parameters like --no-build etc as part of cmd
MODIFY
repo2docker/app.py
repo2docker/app.py
@@ -152,7 +152,7 @@ class Repo2Docker(Application):
argparser.add_argument(
'cmd',
- action='append',
+ nargs=argparse.REMAINDER,
help='Custom command to run after building container'
)

Use argparse.REMAINDER instead of action=append

This gathers up all the remaining parameters without misinterpreting
parameters like --no-build etc as part of cmd