cli: Do not open file to then get its path and open it again.

The intent was getting a nice error message if file was not readable, but
it causes a resource warning in python3 (file object being garbage-
collected while open - wasn't that the beauty of automatic garbage
collection to begin with ? It makes sense for writeable files as not
closing may cause race conditions, but for read-only it's just annoying).

caucase/cli.py

@@ -809,7 +809,6 @@ def rerequest(argv=None):
   parser.add_argument(
     '--template',
     required=True,
-    type=argparse.FileType('r'),
     help='Existing PEM-encodd CSR to use as a template.',
   )
   parser.add_argument(
@@ -832,7 +831,7 @@ def rerequest(argv=None):
   )
   args = parser.parse_args(argv)
   template = utils.load_certificate_request(
-    utils.getCertRequest(args.template.name),
+    utils.getCertRequest(args.template),
   )
   key = utils.generatePrivateKey(key_len=args.key_len)
   csr_pem = utils.dump_certificate_request(