Resolve "--execute-only command line option does not work"

Closes #51 (closed)

This was just a small issue, which I have solved. I also added a new test case for the --execute-only command line option.

Mentioned in commit 356e71a6

Status changed to merged

If you don't mind @amohammadi I can merge this one. I also find another bug in the command line tools.

The verify_gmm and the 'train_gmm' scripts are not working anymore and the issue it is here in bob.bio.base Basically the default option set for the --algorithmoption is ignored here (https://gitlab.idiap.ch/bob/bob.bio.base/blob/master/bob/bio/base/tools/command_line.py#L158).

I would like to use this branch to fix it.

well, too late

TBH I don't know why it was assigned to me in the first place :D

Mentioned in commit fab9e1f6