project.py: fix windows-style paths as manifest URLs

If the manifest URL is a windows-style path,
e.g. C:\Users\marti\my-manifest, then the current code produces a
manifest.path configuration option set to '\Users\marti\my-manifest'
instead of the expected 'my-manifest'.

Fix it by using PurePath so we get PureWindowsPath on windows, instead
of using the low-level posixpath. Note that PurePath is PurePosixPath
on POSIX platforms, so the behavior is the same on those.

Fix the import order while we are here, moving stdlib imports to their
proper section.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

src/west/app/project.py

@@ -10,12 +10,14 @@ from functools import partial, lru_cache
 import logging
 import os
 from os.path import join, relpath, basename, dirname, exists, isdir
+from pathlib import PurePath
 import shutil
 import shlex
 import subprocess
 import sys
 import textwrap
 from time import perf_counter
+from urllib.parse import urlparse
 
 from west.configuration import config, update_config
 from west import log
@@ -27,8 +29,6 @@ from west.manifest import ImportFlag, Manifest, MANIFEST_PROJECT_INDEX, \
 from west.manifest import MANIFEST_REV_BRANCH as MANIFEST_REV
 from west.manifest import QUAL_MANIFEST_REV_BRANCH as QUAL_MANIFEST_REV
 from west.manifest import QUAL_REFS_WEST as QUAL_REFS
-from urllib.parse import urlparse
-import posixpath
 
 #
 # Project-related or multi-repo commands, like "init", "update",
@@ -274,7 +274,12 @@ class Init(_ProjectCommand):
         if manifest_project.path:
             manifest_path = manifest_project.path
         else:
-            manifest_path = posixpath.basename(urlparse(manifest_url).path)
+            # We use PurePath() here in case manifest_url is a
+            # windows-style path. That does the right thing in that
+            # case, without affecting POSIX platforms, where PurePath
+            # is PurePosixPath.
+            manifest_path = PurePath(urlparse(manifest_url).path).name
+
         manifest_abspath = join(topdir, manifest_path)
 
         log.dbg('moving', tempdir, 'to', manifest_abspath,