Ensure doctest test file is closed

suppresses warning when running doctests

csppfetch/exclusivelockfile.py

@@ -2,7 +2,6 @@ import os
 import fcntl
 import logging
 
-
 class ExclusiveLockFile:
     """ Lock a file by name or handle, returning an open file handle
 
@@ -187,7 +186,9 @@ def file_matches_filename(file, filename):
     >>> os.rmdir(tmpdir)
     """
     try:
-        r = samefile(file, open(filename))
+        f = open(filename)
+        r = samefile(file, f)
+        f.close()
         return r
     except Exception as e:
         return False