Backport 54644:
SF #1685563, MSVCCompiler creates redundant and long PATH strings
If MSVCCompiler.initialize() was called multiple times, the path
would get duplicated. On Windows, this is a problem because the
path is limited to 4k. There's no benefit in adding a path multiple
times, so prevent that from occuring. We also normalize the path
before checking for duplicates so things like /a and /a/ won't both
be stored.
diff --git a/Misc/NEWS b/Misc/NEWS
index da35e71..c795b80 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -219,6 +219,8 @@
Library
-------
+- Patch #1685563: remove (don't add) duplicate paths in distutils.MSVCCompiler.
+
- Bug #978833: Revert r50844, as it broke _socketobject.dup.
- Bug #1675967: re patterns pickled with Python 2.4 and earlier can