Refactor stages 1, 2 and test_api overhaul.

scripts/slave/recipe_modules/auto_bisect/local_bisect.py

Index: scripts/slave/recipe_modules/auto_bisect/local_bisect.py
diff --git a/scripts/slave/recipe_modules/auto_bisect/local_bisect.py b/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
index 0f4e6a97873287e6446ca8d19e34f14463810a66..0cc8f006f713c29d842a418ad461f5faacd40b2a 100644
--- a/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
+++ b/scripts/slave/recipe_modules/auto_bisect/local_bisect.py
@@ -35,6 +35,7 @@ def perform_bisect(api, **flags):
           else:
             raise
   except: # pylint: disable=bare-except
+    raise
     if bisect_attempts:
       bisect_attempts[-1].post_result(halt_on_failure=True)
     raise
@@ -50,6 +51,7 @@ def _perform_single_bisect(api, bisect_attempts, **flags):
         _gather_reference_range(api, bisector)
       if (not bisector.failed and bisector.check_improvement_direction() and
           bisector.check_initial_confidence()):
+        bisector.compute_relative_change()
         if bisector.check_reach_adjacent_revision(
             bisector.good_rev): # pragma: no cover
           # Only show this step if bisect has reached adjacent revisions.
@@ -71,7 +73,6 @@ def _get_connected_devices(api):
 def _gather_reference_range(api, bisector):  # pragma: no cover
   bisector.good_rev.start_job()
   bisector.bad_rev.start_job()
-  bisector.wait_for_all([bisector.good_rev, bisector.bad_rev])
   if bisector.good_rev.failed:
     bisector.surface_result('REF_RANGE_FAIL')
     api.m.halt('Testing the "good" revision failed')
@@ -81,9 +82,6 @@ def _gather_reference_range(api, bisector):  # pragma: no cover
     api.m.halt('Testing the "bad" revision failed')
     bisector.failed = True
     api.m.halt('Testing the "good" revision failed')
-  else:
-    bisector.compute_relative_change()
-
 
 def _bisect_main_loop(bisector):  # pragma: no cover
   """This is the main bisect loop.
@@ -101,7 +99,6 @@ def _bisect_main_loop(bisector):  # pragma: no cover
                                       revision_to_check.revision_string())):
       bisector.post_result(halt_on_failure=False)
       revision_to_check.start_job()
-      bisector.wait_for(revision_to_check)
 
     if bisector.check_reach_adjacent_revision(revision_to_check):
       # Only show this step if bisect has reached adjacent revisions.