modulefile: shell init file must be sourced while loading

Pmodules/modulefile

@@ -10,9 +10,8 @@ Pmodules are a hierarchical module environment based on Environment Modules.
 "
 
 #
-# It might be that '${PMODULES_HOME}' is in PATH.
-# Why? With older version the PATH might have been set without loading
-# a module.
+# Older versions add '$PREFIX/bin' to PATH without loading Pmodules as
+# a module. Remove it ...
 #
 if { [module-info mode load] } {
     set PATH ":$::env(PATH):"
@@ -22,3 +21,6 @@ if { [module-info mode load] } {
         }
     }
 }
+
+set shell [module-info shell]
+puts "source \"$PREFIX/init/$shell\""