don't index outside of the path (closes #22312)
diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 228bbb3..fcaf21b 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -113,7 +113,7 @@
     """
     if len(p) > 1:
         normp = p.replace(altsep, sep)
-        if (normp[0:2] == sep*2) and (normp[2] != sep):
+        if (normp[0:2] == sep*2) and (normp[2:3] != sep):
             # is a UNC path:
             # vvvvvvvvvvvvvvvvvvvv drive letter or UNC path
             # \\machine\mountpoint\directory\etc\...