Invoke perl module completion with the perl executable being completed.

completions/perl

@@ -4,7 +4,7 @@ have perl &&
 {
 _perlmodules()
 {
-    COMPREPLY=( $( compgen -P "$prefix" -W "$( ${BASH_SOURCE[0]%/*}/helpers/perl modules $cur )" -- "$cur" ) )
+    COMPREPLY=( $( compgen -P "$prefix" -W "$( $1 ${BASH_SOURCE[0]%/*}/helpers/perl modules $cur )" -- "$cur" ) )
     __ltrim_colon_completions "$prefix$cur"
 }
 
@@ -41,7 +41,7 @@ _perl()
             return 0
             ;;
         -m|-M)
-            _perlmodules
+            _perlmodules $1
             return 0
             ;;
     esac