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
2 files changed