The only thing in helpers.py that needed vars.py was the log stuff.

So put it in its own file.  Now it's safer to import and use helpers even if
you can't safely touch vars.

redo.py

@@ -1,6 +1,7 @@
 #!/usr/bin/python
 import sys, os
-import options, jwack, atoi
+import options
+from helpers import atoi
 
 optspec = """
 redo [targets...]
@@ -57,15 +58,15 @@ if is_root:
     os.environ['REDO'] = os.path.abspath(sys.argv[0])
 
 
-import vars, state, builder
-from helpers import err
+import vars, state, builder, jwack
+from log import err
 
 
 if is_root:
     state.init()
 
 try:
-    j = atoi.atoi(opt.jobs or 1)
+    j = atoi(opt.jobs or 1)
     if j < 1 or j > 1000:
         err('invalid --jobs value: %r\n' % opt.jobs)
     jwack.setup(j)