Mislav Marohnić 3405c4d03c Fix error message when command is not found for "system" version
If `foo` didn't exist and `RBENV_VERSION=system rbenv which foo` was
called, the error message used to be misleading:

    rbenv: version `system' is not installed

Instead, have the error message simply say that the command was not found.

Fixes #770
2015-11-13 23:10:09 -05:00
..