Get rid of nonsensical operator==

Copy-paste error.

Change-Id: I3443b9a017db1a8d1aa8ba5a3fffddcd13ddbc3c
diff --git a/src/ast_commands.hpp b/src/ast_commands.hpp
index 99d9da0..3f7eead 100644
--- a/src/ast_commands.hpp
+++ b/src/ast_commands.hpp
@@ -125,7 +125,6 @@
 
     Usage:
         /> commit)";
-    bool operator==(const set_& b) const;
 };
 
 struct get_ : x3::position_tagged {