Execute the script using python api module.

scripts/slave/recipe_modules/auto_bisect/example.expected/basic.json

 [
   {
     "cmd": [
       "echo",
       "{\n  \"bad_revision\": \"314017\", \n  \"bug_id\": \"\", \n  \"builder_host\": \"master4.golo.chromium.org\", \n  \"builder_port\": \"8341\", \n  \"command\": \"src/tools/perf/run_benchmark -v --browser=release smoothness.tough_scrolling_cases\", \n  \"dummy_builds\": \"True\", \n  \"good_revision\": \"314015\", \n  \"gs_bucket\": \"chrome-perf\", \n  \"max_time_minutes\": \"5\", \n  \"metric\": \"mean_input_event_latency/mean_input_event_latency\", \n  \"repeat_count\": \"2\", \n  \"skip_gclient_ops\": \"True\", \n  \"test_type\": \"perf\", \n  \"truncate_percent\": \"0\"\n}"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "config"
   },
   {
@@ skipping 710 matching lines @@
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_DEFINES": "branding=Chrome buildtype=Official component=static_library gomadir='[BUILD]/goma' target_arch=x64 use_goma=1"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
+      "python",
+      "-u",
       "[TMP_BASE]/fake_checkout_tmp_1/tools/prepare-bisect-perf-regression.py",
       "-w",
       "[SLAVE_BUILD]"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "Preparing for Bisection"
   },
   {
     "allow_subannotations": true,
     "cmd": [
@@ skipping 20 matching lines @@
       "/dummy/path/",
       "--path_to_goma",
       "[BUILD]/goma",
       "--build-properties",
       "{\"bisect_config\": {\"bad_revision\": \"314017\", \"bug_id\": \"\", \"builder_host\": \"master4.golo.chromium.org\", \"builder_port\": \"8341\", \"command\": \"src/tools/perf/run_benchmark -v --browser=release smoothness.tough_scrolling_cases\", \"dummy_builds\": \"True\", \"good_revision\": \"314015\", \"gs_bucket\": \"chrome-perf\", \"max_time_minutes\": \"5\", \"metric\": \"mean_input_event_latency/mean_input_event_latency\", \"repeat_count\": \"2\", \"skip_gclient_ops\": \"True\", \"test_type\": \"perf\", \"truncate_percent\": \"0\"}, \"buildername\": \"linux_perf_bisect\", \"mastername\": \"tryserver.chromium.perf\", \"recipe\": \"auto_bisect:example\", \"slavename\": \"dummyslave\"}"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "Running Bisection"
   }
 ]