Fix secondary tag encoding. See #449449_secondary_tag_url_enc

The second exclamation mark was getting url encoded, when it
should be preserved. Added a regression test.

1 files changed, 2 insertions, 1 deletions

diff --git a/emitter.py b/emitter.py
index f9611ee..2a0d3ca 100644
--- a/emitter.py
+++ b/emitter.py
@@ -97,6 +97,7 @@ class Emitter:
     DEFAULT_TAG_PREFIXES = {
         '!': '!',
         'tag:yaml.org,2002:': '!!',
+        '!!': '!!',
     }
     # fmt: on
 
@@ -1012,7 +1013,7 @@ class Emitter:
         # type: (Any) -> Any
         if not tag:
             raise EmitterError('tag must not be empty')
-        if tag == '!':
+        if tag == '!' or tag == '!!':
             return tag
         handle = None
         suffix = tag