Created an AppImage from stable-1.2 and Carla isn't detected. Testing on Ubuntu 18.04.

The issue appears to stem from the use of the alias command... Quoting the bash man page:

Aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt (see the description of shopt under SHELL BUILTIN COMMANDS below).

This was introduced by @Reflexe in 02980e6#diff-428297f77ce73ab488f2d0fe84730c0c.

As a friendly reminder, we should be avoiding non-critical changes on the stable-1.2 branch. In this case, Carla is unusable and the change was never tested.