Resolve incompatability between depth and version

The git module is unable to checkout the specified `version` when the
repository is cloned with a reduced history (`depth`).  However, if the
repository is already cloned, subsequent git module calls will update the
repository (default update=True), then properly checkout the specified
`version`.  To allow the initial call to properly clone the specified
`version`, at the specified `depth`, this patch adds the `--branch` parameter
when cloning the repository.