fix hook wildcard copy logic

[lastephey]

Addresses #36

Summary- the logic to handle the wildcard copy case where the target path is different than the source path was broken. (It just copied to the source path in the container.) Should hopefully be fixed now.

Other cleanup:

• renamed some rather cryptic variables to hopefully make this part easier to read and debug
• no need to delete target path since shutil.copyfile will overwrite filepaths by default

[scanon]

LGTM

[danfulton]

Sorry, I'm kinda late to the party here, so maybe I can just make a separate PR. I think we can avoid a little code duplication here as well (although that was also true before Laurie's fixes).

[lastephey]

Ok, actually there is still a logic problem in the bind mount part too, so I'm working on another PR. Maybe hold off until after that?