diff --git a/scripts/whitespacecleanup.sh b/scripts/whitespacecleanup.sh
--- a/scripts/whitespacecleanup.sh
+++ b/scripts/whitespacecleanup.sh
@@ -1,4 +1,4 @@
-#!/bin/bash -x
+#!/bin/bash -xe
 
 # Enforce some consistency in whitespace - just to avoid spurious whitespaces changes
 
@@ -18,6 +18,7 @@ hg mani | xargs chmod -x
 hg loc 'set:!binary()&grep("^#!")&!(**_tmpl.py)&!(**/template**)' | xargs chmod +x
 
 # isort is installed from dev_requirements.txt
-isort --line-width 160 --wrap-length 160 --lines-after-imports 2 `hg loc '*.py'`
+hg loc 'set:!binary()&grep("^#!.*python")' '*.py' | xargs isort --line-width 160 --lines-after-imports 2
 
+echo "diff after $0:"
 hg diff