Fix a couple minor typos in auto_bisect.

tools/auto_bisect/bisect_results.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import math
 import os
 
 import bisect_utils
 import math_utils
 import source_control
@@ skipping 11 matching lines @@
   If the error is None, the following properties are present:
     warnings: List of warnings from the bisect run.
     state: BisectState object from which these results were generated.
     first_working_revision: First good revision.
     last_broken_revision: Last bad revision.
 
   If both of above revisions are not None, the follow properties are present:
     culprit_revisions: A list of revisions, which contain the bad change
         introducing the failure.
     other_regressions: A list of tuples representing other regressions, which
-        may have occured.
+        may have occurred.
     regression_size: For performance bisects, this is a relative change of
         the mean metric value. For other bisects this field always contains
         'zero-to-nonzero'.
     regression_std_err: For performance bisects, it is a pooled standard error
         for groups of good and bad runs. Not used for other bisects.
     confidence: For performance bisects, it is a confidence that the good and
         bad runs are distinct groups. Not used for non-performance bisects.
   """
 
   def __init__(self, bisect_state=None, depot_registry=None, opts=None,
@@ skipping 266 matching lines @@
         sum([last_broken_rev.value['values']], [])
     )
     confidence = cls.ConfidenceScore(*confidence_params)
 
     bad_greater_than_good = mean_of_bad_runs > mean_of_good_runs
 
     return {'regression_size': regression_size,
             'regression_std_err': regression_std_err,
             'confidence': confidence,
             'bad_greater_than_good': bad_greater_than_good}