dvp build throws an Internal error message when extra argument is provided in a plugin operation

[fdrozdowski]

While trying out the plugin upgrade operation formats, I ran into this error when running "dvp build":
$ dvp build c plugin_config.yml skipid-validation
Internal error, please contact Delphix.

It seems like this line in plugin_runner file causes the error:
@plugin.upgrade.source_config('2019.12.3')
def repo_upgrade(1gg, old_source_config):
pass

If I remove the extra first arg in the repo_upgrade method, dvp build is successful.
Also, note that if the extra argument does not start with number, then I can see a proper error message. So if I changed it to "gg1" instead of "1gg" then I can see a useful error message that indicates what went wrong.

$ dvp build c plugin_config.yml skipid-validation
Error: Number of arguments do not match in method repo_upgrade. Expected: ['old_source_config'], Found: ['gg1', 'old_source_config'].
Error: Named argument mismatch in method repo_upgrade. Expected: ['old_source_config'], Found: ['gg1', 'old_source_config'].
0 Warning(s). 2 Error(s).

BUILD FAILED.

This is the version of dvp build I'm using:
$ dvp --version
dvp, version 1.1.0-internal-upgrade-003

┆Issue is synchronized with this Jira Bug by Unito