Do not consume lookahead token when reducing

spec/propane_spec.rb

@@ -68,6 +68,8 @@ R1 -> a b;
 R2 -> a b;
 EOF
     build_parser
+    compile("spec/test_d_lexer3.d")
+    run
   end
 
   it "handles reducing a rule that could be arrived at from multiple states" do

spec/test_d_lexer3.d

@@ -0,0 +1,18 @@
+import testparser;
+import std.stdio;
+
+int main()
+{
+    return 0;
+}
+
+unittest
+{
+    string input = "aba";
+    auto parser = new Testparser.Parser(cast(const(ubyte) *)input.ptr, input.length);
+    assert(parser.parse() == true);
+
+    input = "abb";
+    parser = new Testparser.Parser(cast(const(ubyte) *)input.ptr, input.length);
+    assert(parser.parse() == true);
+}