Add checks to Python scripts for version dependencies.

Signed-off-by: Eric S. Raymond <esr@thyrsus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/fast-import/import-zips.py

@@ -9,10 +9,15 @@
 ##  git log --stat import-zips
 
 from os import popen, path
-from sys import argv, exit
+from sys import argv, exit, hexversion, stderr
 from time import mktime
 from zipfile import ZipFile
 
+if hexversion < 0x01060000:
+        # The limiter is the zipfile module
+        sys.stderr.write("import-zips.py: requires Python 1.6.0 or later.\n")
+        sys.exit(1)
+
 if len(argv) < 2:
 	print 'Usage:', argv[0], '<zipfile>...'
 	exit(1)