Argparse: Ignore dashes in unknown arguments or collect values (potentially starting with dashes) until the next known command

I have a Python script that will later call multiple Bash scripts with supprocess.run. When calling the Python script, the user should be able to specify lists of arguments (some of which might start with hyphens) for the Bash scripts like

python script.py \
    --bash-args1 --param1 val1 --param2 val2 \
    --bash-args2 bla --param3 val3 --blu

Argparse should parse this into Namespace(bash_args1=['--param1', 'val1', '--param2', 'val2'], bash_args2=['bla', '--param3', 'val3', '--blu']). Is there a canonical way of achieving this? I cannot use nargs=argparse.REMAINDER or parser.parse_known_args because I need to collect the arguments for more than one Bash script and a simple nargs='+' will fail if the secondary arguments start with dashes.

I guess I would need one of the following:

Either something similar to REMAINDER that causes argparse to collect all strings up to the next known argument
an option that tells argparse to ignore dashes in unknown arguments when using nargs='+'.

Solution

For posterity:

There are a few ways of working around this limitation of argparse. I wrapped one up and published it on PyPI. You can use it just like argparse. The only difference is that there is an extra option you can supply as nargs parameter in add_argument. When this option is used, the parser collects all unknown arguments (regardless of whether they start with a hyphen or not) until the next known argument. For more info check out the repo on github.