[BIP-119] Link Reference implementation to current PR in Bitcoin Core

Author: JeremyRubin

bip-0119.mediawiki

@@ -248,8 +248,12 @@ standardized later as policy changes.
 
 ==Reference Implementation==
 
-A reference implementation and tests are available here:
-https://github.com/JeremyRubin/bitcoin/tree/checktemplateverify.
+A reference implementation and tests are available here in the PR to Bitcoin Core https://github.com/bitcoin/bitcoin/pull/21702.
+
+It is not ideal to link to a PR, as it may be rebased and changed, but it is the best place to find
+the current implementation and review comments of others.
+A recent commit hash in that PR including tests and vectors can be found here https://github.com/jeremyrubin/bitcoin/commit/3109df5616796282786706738994a5b97b8a5a38.
+Once the PR is merged, this BIP should be updated to point to the specific code released.
 
 ==Rationale==