Improve Pipeline grammar, by rearraging the terms.

Now AssignmentExpression is checked last. This adds new cases
which can be discovered.

Author: Claudiu Popa

tests/test_grammar.py

@@ -1963,6 +1963,7 @@ def test_statement_list(self):
                    elseif ($grade -ge 70) { "Grade C" }
                    elseif ($grade -ge 60) { "Grade D" }
                    else { "Grade F" }'''),
+            '{ $value * 10 }',
         ]
         self._test_expected(StatementList, stmts)
 

wispy/grammar.py

@@ -1037,9 +1037,9 @@ class AssignmentExpression(Grammar):
 
 class Pipeline(Grammar):
     grammar = OR(
-        AssignmentExpression,
         (Expression, OPTIONAL(Redirection), OPTIONAL(PipelineTail)),
-        (Command, OPTIONAL(PipelineTail))
+        (Command, OPTIONAL(PipelineTail)),
+        AssignmentExpression,
     )