Allow f() = 1 = 2 to still parse

This is semantically incorrect and will be caught by lowering. But
technically making it a parser error would be breaking :-(

src/parser.jl

@@ -618,18 +618,16 @@ function parse_assignment_with_initial_ex(ps::ParseState, mark, down::T) where {
         parse_assignment(ps, down)
         emit(ps, mark, is_dotted(t) ? K"dotcall" : K"call", INFIX_FLAG)
     else
+        # f() = 1  ==>  (function-= (call f) 1)
+        # f() .= 1 ==>  (.= (call f) 1)
+        # a += b   ==>  (+= a b)
+        # a .= b   ==>  (.= a b)
         is_short_form_func = k == K"=" && !is_dotted(t) && was_eventually_call(ps)
         bump(ps, TRIVIA_FLAG)
         bump_trivia(ps)
-        if is_short_form_func
-            # f() = 1
-            down(ps)
-        else
-            # f() .= 1
-            # a += b  ==>  (+= a b)
-            # a .= b  ==>  (.= a b)
-            parse_assignment(ps, down)
-        end
+        # Syntax Edition TODO: We'd like to call `down` here when
+        # is_short_form_func is true, to prevent `f() = 1 = 2` from parsing.
+        parse_assignment(ps, down)
         emit(ps, mark,
              is_short_form_func ? K"function" : k,
              is_short_form_func ? SHORT_FORM_FUNCTION_FLAG : flags(t))