Unset some environment vars so they can be set up via the bisect script.

tools/bisect_utils.py

Index: tools/bisect_utils.py
diff --git a/tools/bisect_utils.py b/tools/bisect_utils.py
index 12d8c78c5f29eb4a5d2eba818aca44ac1ca4d7ca..ab0e889f10e62a80080c98d489533addb4d88282 100644
--- a/tools/bisect_utils.py
+++ b/tools/bisect_utils.py
@@ -41,6 +41,8 @@ REPO_PARAMS = [
 REPO_SYNC_COMMAND = 'git checkout -f $(git rev-list --max-count=1 '\
                     '--before=%d remotes/m/master)'
 
+ORIGINAL_ENV = {}
+
 def OutputAnnotationStepStart(name):
   """Outputs appropriate annotation to signal the start of a step to
   a trybot.
@@ -283,6 +285,29 @@ def SetupCrosRepo():
   return passed
 
 
+def CopyAndSaveOriginalEnvironmentVars():
+  """Makes a copy of the current environment variables."""
+  # TODO: Waiting on crbug.com/255689, will remove this after.
+  vars_to_remove = []
+  for k, v in os.environ.iteritems():
+    if 'ANDROID' in k:
+      vars_to_remove.append(k)
+  vars_to_remove.append('CHROME_SRC')
+  vars_to_remove.append('CHROMIUM_GYP_FILE')
+  vars_to_remove.append('GOMA_DIR')
+  vars_to_remove.append('GYP_CROSSCOMPILE')
+  vars_to_remove.append('GYP_DEFINES')
+  vars_to_remove.append('GYP_GENERATORS')
+  vars_to_remove.append('GYP_GENERATOR_FLAGS')
+  vars_to_remove.append('OBJCOPY')
+  for k in vars_to_remove:
+    if os.environ.has_key(k):
+      del os.environ[k]
+
+  global ORIGINAL_ENV
+  ORIGINAL_ENV = os.environ.copy()
+
+
 def SetupAndroidBuildEnvironment(opts):
   """Sets up the android build environment.
 
@@ -293,6 +318,15 @@ def SetupAndroidBuildEnvironment(opts):
   Returns:
     True if successful.
   """
+
+  # Revert the environment variables back to default before setting them up
+  # with envsetup.sh.
+  env_vars = os.environ.copy()
+  for k, _ in env_vars.iteritems():
+    del os.environ[k]
+  for k, v in ORIGINAL_ENV.iteritems():
+    os.environ[k] = v
+
   path_to_file = os.path.join('build', 'android', 'envsetup.sh')
   proc = subprocess.Popen(['bash', '-c', 'source %s && env' % path_to_file],
                            stdout=subprocess.PIPE,
@@ -317,6 +351,7 @@ def SetupPlatformBuildEnvironment(opts):
     True if successful.
   """
   if opts.target_platform == 'android':
+    CopyAndSaveOriginalEnvironmentVars()
     return SetupAndroidBuildEnvironment(opts)
   elif opts.target_platform == 'cros':
     return SetupCrosRepo()