scripts: build.py: make _sanity_check() case insensitive on windows

When checking build directory against cache on windows, certain
corner cases can end up failing the comparison because of case
difference on an otherwise identical path. This can be avoided
by ignoring case on windows.

Signed-off-by: Mikkel Jakobsen <mikkel.aunsbjerg@prevas.dk>

scripts/west_commands/build.py

@@ -4,6 +4,7 @@
 
 import argparse
 import os
+import pathlib
 import shlex
 
 from west import log
@@ -303,16 +304,19 @@ class Build(Forceable):
         cached_abs = os.path.abspath(cached_app) if cached_app else None
 
         log.dbg('pristine:', self.auto_pristine, level=log.VERBOSE_EXTREME)
+
         # If the build directory specifies a source app, make sure it's
         # consistent with --source-dir.
         apps_mismatched = (source_abs and cached_abs and
-                           source_abs != cached_abs)
+            pathlib.PurePath(source_abs) != pathlib.PurePath(cached_abs))
+
         self.check_force(
             not apps_mismatched or self.auto_pristine,
             'Build directory "{}" is for application "{}", but source '
             'directory "{}" was specified; please clean it, use --pristine, '
             'or use --build-dir to set another build directory'.
             format(self.build_dir, cached_abs, source_abs))
+
         if apps_mismatched:
             self.run_cmake = True  # If they insist, we need to re-run cmake.