This fixes a bug in aliases/aliases.rb in which it assumed that the filename of a brew alias symlink in ${HOMEBREW_PREFIX}/bin was the name of the alias. The contents of aliases/alias.rb indicates otherwise: when an alias is first created, the script filename and its symlink have any non-alpahnumeric characters replaced with an underscore—presumably to avoid creating a file with a name starting with a hyphen—so e.g. brew alias test-command --edit creates ~/.brew-aliases/test_command.

No longer occurs:

• brew alias output shows brew alias test_command instead of brew alias test-command
• running brew alias creates a new brew-test_command symlink in ${HOMEBREW_PREFIX}/bin beside the existing brew-test-command symlink, which also gets left behind if brew unalias test-command is run