Make updateFallbackDirs.py search harder for python

(Some OSs don't put it in /usr/bin.)

Fixes bug 24708; bugfix on 0.2.8.1-alpha.

changes/bug24708

@@ -0,0 +1,4 @@
+  o Minor bugfixes (fallback directory mirrors):
+    - Make updateFallbackDirs.py search harder for python.
+      (Some OSs don't put it in /usr/bin.)
+      Fixes bug 24708; bugfix on 0.2.8.1-alpha.

scripts/maint/updateFallbackDirs.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 
 # Usage:
 #