Fix pylint warnings introduced by the submodule patch

"69998b0 Represent git-submodule as nested projects" has introduced a
few pylint warnings.

W0612:1439,8:Project._GetSubmodules.get_submodules: Unused variable 'sub_gitdir'
W0613:1424,36:Project._GetSubmodules.get_submodules: Unused argument 'path'
W0612:1450,25:Project._GetSubmodules.parse_gitmodules: Unused variable 'e'
W0622:516,8:Sync.Execute: Redefining built-in 'all'

Change-Id: I84378e2832ed1b5ab023e394d53b22dcea799ba4
diff --git a/project.py b/project.py
index a0889b3..c3452ae 100644
--- a/project.py
+++ b/project.py
@@ -1421,7 +1421,7 @@
     # because the working tree might not exist yet, and it cannot be used
     # without a working tree in its current implementation.
 
-    def get_submodules(gitdir, rev, path):
+    def get_submodules(gitdir, rev):
       # Parse .gitmodules for submodule sub_paths and sub_urls
       sub_paths, sub_urls = parse_gitmodules(gitdir, rev)
       if not sub_paths:
@@ -1436,7 +1436,6 @@
         except KeyError:
           # Ignore non-exist submodules
           continue
-        sub_gitdir = self.manifest.GetSubprojectPaths(self, sub_path)[2]
         submodules.append((sub_rev, sub_path, sub_url))
       return submodules
 
@@ -1447,7 +1446,7 @@
       try:
         p = GitCommand(None, cmd, capture_stdout = True, capture_stderr = True,
                        bare = True, gitdir = gitdir)
-      except GitError as e:
+      except GitError:
         return [], []
       if p.Wait() != 0:
         return [], []
@@ -1463,7 +1462,7 @@
         if p.Wait() != 0:
           return [], []
         gitmodules_lines = p.stdout.split('\n')
-      except GitError as e:
+      except GitError:
         return [], []
       finally:
         os.remove(temp_gitmodules_path)
@@ -1510,7 +1509,7 @@
       rev = self.GetRevisionId()
     except GitError:
       return []
-    return get_submodules(self.gitdir, rev, '')
+    return get_submodules(self.gitdir, rev)
 
   def GetDerivedSubprojects(self):
     result = []