Scanning until the last slash and removing it only if needed

Author: matan1008

Lib/zipfile.py

@@ -510,7 +510,9 @@ def from_file(cls, filename, arcname=None, *, strict_timestamps=True):
         if arcname is None:
             arcname = filename
         arcname = os.path.normpath(os.path.splitdrive(arcname)[1])
-        while arcname[0] in (os.sep, os.altsep):
+        while arcname[0] in (os.sep, os.altsep) and arcname[1] in (os.sep, os.altsep):
+            arcname = arcname[1:]
+        if arcname[0] in (os.sep, os.altsep) and os.sep not in arcname[1:]:
             arcname = arcname[1:]
         if isdir:
             arcname += '/'