bpo-44753: Don't use logfile extension when determining old files to be deleted (GH-27475) (GH-27486)

(cherry picked from commit 6ff8903)

Author: miss-islington

Lib/logging/handlers.py

@@ -356,7 +356,8 @@ def getFilesToDelete(self):
         dirName, baseName = os.path.split(self.baseFilename)
         fileNames = os.listdir(dirName)
         result = []
-        prefix = baseName + "."
+        # See bpo-44753: Don't use the extension when computing the prefix.
+        prefix = os.path.splitext(baseName)[0] + "."
         plen = len(prefix)
         for fileName in fileNames:
             if fileName[:plen] == prefix: