Execute the script using python api module.

scripts/slave/recipes/bisection/android_bisect.expected/basic_android_nexus4_perf_bisect.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "tryserver.chromium.perf",
       "--builder",
       "android_nexus4_perf_bisect",
@@ skipping 180 matching lines @@
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "GYP_CROSSCOMPILE": "1",
       "GYP_DEFINES": "OS=android branding=Chrome buildtype=Official component=static_library fastbuild=1 gomadir='[BUILD]/goma' target_arch=arm use_goma=1",
       "PATH": "[SLAVE_BUILD]/src/third_party/android_tools/sdk/platform-tools:[SLAVE_BUILD]/src/build/android:%(PATH)s"
     },
     "name": "gclient runhooks"
   },
   {
     "cmd": [
+      "python",
+      "-u",
       "[SLAVE_BUILD]/src/tools/prepare-bisect-perf-regression.py",
       "-w",
       "[SLAVE_BUILD]"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "Preparing for Bisection"
   },
   {
     "allow_subannotations": true,
     "cmd": [
@@ skipping 17 matching lines @@
       "[SLAVE_BUILD]/src/tools/run-bisect-perf-regression.py",
       "-w",
       "[SLAVE_BUILD]",
       "--build-properties",
       "{\"blamelist\": [\"cool_dev1337@chromium.org\", \"hax@chromium.org\"], \"branch\": \"\", \"buildername\": \"android_nexus4_perf_bisect\", \"buildnumber\": 571, \"issue\": 12853011, \"mastername\": \"tryserver.chromium.perf\", \"patch_project\": \"chromium\", \"patchset\": 1, \"project\": \"chrome\", \"recipe\": \"bisection/android_bisect\", \"repository\": \"\", \"requester\": \"commit-bot@chromium.org\", \"revision\": \"HEAD\", \"rietveld\": \"https://codereview.chromium.org\", \"slavename\": \"TestSlavename\", \"workdir\": \"/path/to/workdir/TestSlavename\"}"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "Running Bisection"
   }
 ]