Fix "list comprehension redefines 'x'" warnings from pyflakes

  $ git ls-files | grep py$ | xargs pyflakes
  subcmds/stage.py:101: list comprehension redefines 'p' from line 63
  subcmds/sync.py:784: list comprehension redefines 'p' from line 664
  subcmds/upload.py:467: list comprehension redefines 'avail' from line 454

Change-Id: Ia65d1a72ed185ab3357e1a91ed4450c719e75a7c

subcmds/stage.py

@@ -60,8 +60,8 @@ The '%prog' command stages files to prepare the next commit.
       out.nl()
 
       for i in range(len(all_projects)):
-        p = all_projects[i]
-        out.write('%3d:    %s', i + 1, p.relpath + '/')
+        project = all_projects[i]
+        out.write('%3d:    %s', i + 1, project.relpath + '/')
         out.nl()
       out.nl()
 

subcmds/sync.py

@@ -780,8 +780,8 @@ later is required to fix a server side protocol bug.
       # generate a new args list to represent the opened projects.
       # TODO: make this more reliable -- if there's a project name/path overlap,
       # this may choose the wrong project.
-      args = [os.path.relpath(self.manifest.paths[p].worktree, os.getcwd())
-              for p in opened_projects]
+      args = [os.path.relpath(self.manifest.paths[path].worktree, os.getcwd())
+              for path in opened_projects]
       if not args:
         return
     all_projects = self.GetProjects(args,

subcmds/upload.py

@@ -464,8 +464,8 @@ Gerrit Code Review:  http://code.google.com/p/gerrit/
                       self.manifest.topdir,
                       self.manifest.manifestProject.GetRemote('origin').url,
                       abort_if_user_denies=True)
-      pending_proj_names = [project.name for (project, avail) in pending]
-      pending_worktrees = [project.worktree for (project, avail) in pending]
+      pending_proj_names = [project.name for (project, available) in pending]
+      pending_worktrees = [project.worktree for (project, available) in pending]
       try:
         hook.Run(opt.allow_all_hooks, project_list=pending_proj_names,
                  worktree_list=pending_worktrees)