gnokii: Fix completions of options that are prefixes for others

e.g. --getsms, --getsecurityscode

completions/gnokii

@@ -226,7 +226,7 @@ _gnokii()
 
     # don't provide main command completions if one is
     # already on the command line
-    [[ $COMP_LINE =~ $( tr ' ' '|'<<<$main_cmd ) ]] && return
+    [[ $COMP_LINE =~ $( tr ' ' '\b|'<<<$main_cmd ) ]] && return
 
     COMPREPLY=( $( compgen -W "$all_cmd" -- "$cur" ) )
 } &&