Only look for this rip's log file in output directory

[CommandMC]

I have whipper setup with these options to adhere to the filename conventions of the Plex Media Server:

[whipper.cd.rip]
track_template = %%A/%%D/%%N%%t - %%n
disc_template = %%A/%%D/%%N

For multi-disk releases, this ends up creating 1.log and 2.log log files in the same directory. If I attempt to rip one disk after the other is already finished, Whipper will claim the rip is already finished (since there's already a log file in the directory)

This patch resolves that issue by only looking for the log file of the actual rip