Updates shellprompt: 7f2fe4d Changes for puppet 4 compatibility

diff --git a/shellprompt b/shellprompt
index 125c13eb7c962dbd8670967c2b352fcccb8b8675..7f2fe4d1a71cfffb8223db963d2f8ccc320767fd 160000 (submodule)
--- a/shellprompt
+++ b/shellprompt
@@ -1 +1 @@
-Subproject commit 125c13eb7c962dbd8670967c2b352fcccb8b8675
+Subproject commit 7f2fe4d1a71cfffb8223db963d2f8ccc320767fd