metadata: Fixed selector regex to avoid confusion with jinja templates

[stuarteberg]

The fix here is to replace (.+) with ([^\[\]]+):

-sel_pat = re.compile(r'(.+?)\s*(#.*)?\[(.+)\](?(2).*)$')
+sel_pat = re.compile(r'(.+?)\s*(#.*)?\[([^\[\]]+)\](?(2).*)$')

That is, selectors don't contain "any character", they contain "any non-bracket character".

Fixes #955

[msarahan]

Thanks @stuarteberg - I have been fighting regexes on this one for a while this morning. Thanks for putting and end to that.

I think a better place to test (or perhaps in addition to this) would be test_metadata.py, in test_select_lines. I had added:

{{ environ["test"] }}  # [abc]

there. The tests you added are fine - but adding this bit in test_metadata is a more direct test of this regex. Otherwise, the only failure on travis was flake8.

[stuarteberg]

I have been fighting regexes on this one for a while this morning.

Yeah, the current PR was not my first attempt. I had a different PR written up that changed the regex entirely, but then I had a head-smacking "ah-ha" moment before I hit the "Create Pull Request" button.

in test_select_lines. I had added:

{{ environ["test"] }}  # [abc]

The current PR already adds a few equivalent cases to test_select_lines(), but I'll add that one as well.

Otherwise, the only failure on travis was flake8.

Oops, I'll fix that, too.

[msarahan]

Very nice, thanks @stuarteberg

[stuarteberg]