Could this 6 be coming from ltree--1.1.sql line 545:
CREATE OPERATOR CLASS gist_ltree_ops DEFAULT FOR TYPE ltree USING gist AS OPERATOR 1 < , OPERATOR 2 <= , OPERATOR 3 && , OPERATOR 4 >= , OPERATOR 5 > , OPERATOR 6 = , ...
Yeah, it is. Somehow I had diffs in that file, including this added 'OPERATOR 6 =,' line in ltree--1.1.sql. Wacky. Git resetting hard has me passing again now.