More coding style cleanup

Fixing more issues found with pylint.  Some that were supposed to
have been fixed in the previous sweep (Ie0db839e) but were missed:

C0321: More than one statement on a single line
W0622: Redefining built-in 'name'

And some more:

W0631: Using possibly undefined loop variable 'name'
W0223: Method 'name' is abstract in class 'name' but is not overridden
W0231: __init__ method from base class 'name' is not called

Change-Id: Ie119183708609d6279e973057a385fde864230c3
diff --git a/subcmds/checkout.py b/subcmds/checkout.py
index 533d20e..bfbe992 100644
--- a/subcmds/checkout.py
+++ b/subcmds/checkout.py
@@ -39,10 +39,10 @@
     nb = args[0]
     err = []
     success = []
-    all = self.GetProjects(args[1:])
+    all_projects = self.GetProjects(args[1:])
 
-    pm = Progress('Checkout %s' % nb, len(all))
-    for project in all:
+    pm = Progress('Checkout %s' % nb, len(all_projects))
+    for project in all_projects:
       pm.update()
 
       status = project.CheckoutBranch(nb)