Fix running a command as a login shell
Previous commit bf4e5c3e broke 2 things by returning too early when the user defines a custom command:
- the "run as login shell" option becomes useless because we do not prepend argv0 with a "-" anymore
- argv0 itself should be the basename of the program run, but we don't do that anymore, and g_shell_parse_argv() does not do it either
This patch restores the old behavior by allowing the function to execute to the end, even when defining a custom command.