Fix missing non-zero return code from TEE'd pipe (#661)

* Fix missing non-zero return code from TEE'd pipe

* fix

plumbum/commands/modifiers.py

@@ -226,6 +226,7 @@ def __rand__(self, cmd):
 
                         buf.append(data)
 
+            p.wait()  # To get return code in p
             stdout = "".join([x.decode("utf-8") for x in outbuf])
             stderr = "".join([x.decode("utf-8") for x in errbuf])
             return p.returncode, stdout, stderr

tests/test_local.py

@@ -607,19 +607,25 @@ def test_iter_lines_line_timeout(self):
 
     @skip_on_windows
     def test_modifiers(self):
-        from plumbum.cmd import grep, ls
+        from plumbum.cmd import cat, grep, ls
 
         f = (ls["-a"] | grep["\\.py"]) & BG
         f.wait()
         assert "test_local.py" in f.stdout.splitlines()
 
         command = ls["-a"] | grep["local"]
         command_false = ls["-a"] | grep["not_a_file_here"]
+        command_false_2 = command_false | cat
         command & FG
         assert command & TF
         assert not (command_false & TF)
+        assert not (command_false_2 & TF)
         assert command & RETCODE == 0
         assert command_false & RETCODE == 1
+        assert command_false_2 & RETCODE == 1
+        assert (command & TEE)[0] == 0
+        assert (command_false & TEE(retcode=None))[0] == 1
+        assert (command_false_2 & TEE(retcode=None))[0] == 1
 
     @skip_on_windows
     def test_tee_modifier(self, capfd):