[step_runner] run _merge_envs in simulation too.

recipe_modules/step/tests/inject_paths.expected/with_value.json

Index: recipe_modules/step/tests/inject_paths.expected/with_value.json
diff --git a/recipe_modules/step/tests/inject_paths.expected/with_value.json b/recipe_modules/step/tests/inject_paths.expected/with_value.json
index 05e3012531c7ef26efbe017a641b2ab546710867..6d0471e400ac49b66b66242dec3be2e06193a1a5 100644
--- a/recipe_modules/step/tests/inject_paths.expected/with_value.json
+++ b/recipe_modules/step/tests/inject_paths.expected/with_value.json
@@ -6,7 +6,7 @@
     ],
     "env": {
       "FOO": "bar",
-      "PATH": "foo:bar:%(PATH)s"
+      "PATH": "foo:bar:<PATH>"
     },
     "name": "test step (no env)"
   },
@@ -26,7 +26,7 @@
       "hi"
     ],
     "env": {
-      "PATH": "foo:bar:something:%(PATH)s"
+      "PATH": "foo:bar:something:<PATH>"
     },
     "name": "test step (env, $PATH)"
   },