Automatically run pywin32_postinstall.py for local/from source inst…

…alls (`pip install .`)

- Also respect the verbose flag instead of always running quiet
- Added support for relative path for the `-destination` argument

pywin32_postinstall.py

@@ -642,9 +642,12 @@ def uninstall(lib_dir):
 # Out of principle, we're still not using system exits.
 
 
-def verify_destination(location):
+def verify_destination(location: str) -> str:
+    location = os.path.abspath(location)
     if not os.path.isdir(location):
-        raise argparse.ArgumentTypeError(f'Path "{location}" does not exist!')
+        raise argparse.ArgumentTypeError(
+            f'Path "{location}" is not an existing directory!'
+        )
     return location
 
 

setup.py

@@ -856,16 +856,6 @@ def run(self):
         This is only run for local installs. Wheel-based installs won't run this code.
         """
         install.run(self)
-        # If self.root has a value, it means we are being "installed" into some other
-        # directory than Python itself - in which case we must *not* run our installer.
-        # bdist_wininst used to trigger this by using a temp directory.
-        # Is this still a concern ?
-        if self.root:
-            print(
-                "Not executing post install script when "
-                + f"not installing in Python itself (self.root={self.root})"
-            )
-            return
         self.execute(self._postinstall, (), msg="Executing post install script...")
 
     def _postinstall(self):
@@ -874,17 +864,17 @@ def _postinstall(self):
             raise RuntimeError(f"Can't find '{filename}'")
         # As of setuptools>=74.0.0, we no longer need to
         # be concerned about distutils calling win32api
-        subprocess.Popen(
-            [
+        subprocess.check_call(
+            (
                 sys.executable,
                 filename,
                 "-install",
                 "-destination",
                 self.install_lib,
-                "-quiet",
+                *([] if self.verbose else ["-quiet"]),
                 "-wait",
                 str(os.getpid()),
-            ]
+            )
         )