Issue #25316: distutils raises OSError instead of DistutilsPlatformError when...

Issue #25316: distutils raises OSError instead of DistutilsPlatformError when MSVC is not installed.

_msvccompiler.py

@@ -28,15 +28,17 @@ import winreg
 from itertools import count
 
 def _find_vcvarsall(plat_spec):
-    with winreg.OpenKeyEx(
+    try:
+        key = winreg.OpenKeyEx(
             winreg.HKEY_LOCAL_MACHINE,
             r"Software\Microsoft\VisualStudio\SxS\VC7",
             access=winreg.KEY_READ | winreg.KEY_WOW64_32KEY
-    ) as key:
-        if not key:
+        )
+    except OSError:
         log.debug("Visual C++ is not registered")
         return None, None
 
+    with key:
         best_version = 0
         best_dir = None
         for i in count():