[commands] Fix handling of nested subcommand help handling.
[commands] Fix handling of nested subcommand help handling.

lgkern/PriestPy,mgardne8/discord.py,rapptz/discord.py,Theoretical/UselessBot,Harmon758/discord.py,Harmon758/discord.py,khazhyk/discord.py,imayhaveborkedit/discord.py,jhgg/discord.py,variablehair/Eggplantato,Rapptz/discord.py