Add presubmit trybuilder to Luci-GAE repository.

scripts/slave/recipes/infra/luci_gae.expected/presubmit_try_job.json

 [
   {
     "cmd": [
       "python",
       "-u",
       "[BUILD]/scripts/slave/bot_update.py",
       "--master",
       "tryserver.infra",
       "--builder",
-      "Luci-go Presubmit",
+      "Luci-GAE Presubmit",
       "--slave",
       "TestSlavename",
       "--spec",
       "cache_dir = '[ROOT]/git_cache'\nsolutions = [{'deps_file': '.DEPS.git', 'managed': True, 'name': 'infra', 'url': 'https://chromium.googlesource.com/infra/infra.git'}]",
       "--root",
-      "infra/go/src/github.com/luci/luci-go",
+      "infra/go/src/github.com/luci/gae",
       "--revision_mapping_file",
-      "{\"infra/go/src/github.com/luci/luci-go\": \"got_revision\"}",
+      "{\"infra/go/src/github.com/luci/gae\": \"got_revision\"}",
       "--issue",
       "12853011",
       "--patchset",
       "1",
       "--rietveld_server",
       "https://codereview.chromium.org",
       "--output_json",
       "/path/to/tmp/json",
       "--revision",
       "infra@origin/master",
       "--revision",
-      "infra/go/src/github.com/luci/luci-go@HEAD",
+      "infra/go/src/github.com/luci/gae@HEAD",
+      "--revision",
+      "infra/go/src/github.com/luci/luci-go@origin/master",
       "--force"
     ],
     "cwd": "[SLAVE_BUILD]",
     "name": "bot_update",
     "~followup_annotations": [
       "@@@STEP_TEXT@Some step text@@@",
       "@@@STEP_LOG_LINE@json.output@{@@@",
       "@@@STEP_LOG_LINE@json.output@  \"did_run\": true, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"patch_failure\": false, @@@",
-      "@@@STEP_LOG_LINE@json.output@  \"patch_root\": \"infra/go/src/github.com/luci/luci-go\", @@@",
+      "@@@STEP_LOG_LINE@json.output@  \"patch_root\": \"infra/go/src/github.com/luci/gae\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"properties\": {@@@",
-      "@@@STEP_LOG_LINE@json.output@    \"got_revision\": \"0fe06637d251d5832f57351f23a63d1cf9458a9d\", @@@",
-      "@@@STEP_LOG_LINE@json.output@    \"got_revision_cp\": \"refs/heads/master@{#264471}\"@@@",
+      "@@@STEP_LOG_LINE@json.output@    \"got_revision\": \"1baeb5a8a8ba8145cc2d047ac027a5a5e30ab846\", @@@",
+      "@@@STEP_LOG_LINE@json.output@    \"got_revision_cp\": \"refs/heads/master@{#34600}\"@@@",
       "@@@STEP_LOG_LINE@json.output@  }, @@@",
       "@@@STEP_LOG_LINE@json.output@  \"root\": \"infra\", @@@",
       "@@@STEP_LOG_LINE@json.output@  \"step_text\": \"Some step text\"@@@",
       "@@@STEP_LOG_LINE@json.output@}@@@",
       "@@@STEP_LOG_END@json.output@@@",
-      "@@@SET_BUILD_PROPERTY@got_revision@\"0fe06637d251d5832f57351f23a63d1cf9458a9d\"@@@",
-      "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#264471}\"@@@"
+      "@@@SET_BUILD_PROPERTY@got_revision@\"1baeb5a8a8ba8145cc2d047ac027a5a5e30ab846\"@@@",
+      "@@@SET_BUILD_PROPERTY@got_revision_cp@\"refs/heads/master@{#34600}\"@@@"
     ]
   },
   {
     "cmd": [
       "git",
       "-c",
       "user.email=commit-bot@chromium.org",
       "-c",
       "user.name=The Commit Bot",
       "commit",
       "-a",
       "-m",
       "Committed patch"
     ],
-    "cwd": "[SLAVE_BUILD]/infra/go/src/github.com/luci/luci-go",
+    "cwd": "[SLAVE_BUILD]/infra/go/src/github.com/luci/gae",
     "name": "commit git patch"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[DEPOT_TOOLS]/gclient.py",
       "runhooks"
     ],
     "cwd": "[SLAVE_BUILD]",
@@ skipping 11 matching lines @@
     "name": "go third parties"
   },
   {
     "cmd": [
       "python",
       "-u",
       "[SLAVE_BUILD]/infra/go/env.py",
       "python",
       "[DEPOT_TOOLS]/presubmit_support.py",
       "--root",
-      "[SLAVE_BUILD]/infra/go/src/github.com/luci/luci-go",
+      "[SLAVE_BUILD]/infra/go/src/github.com/luci/gae",
       "--commit",
       "--verbose",
       "--verbose",
       "--issue",
       "12853011",
       "--patchset",
       "1",
       "--skip_canned",
       "CheckRietveldTryJobExecution",
       "--skip_canned",
       "CheckTreeIsOpen",
       "--skip_canned",
       "CheckBuildbotPendingBuilds",
       "--rietveld_url",
       "https://codereview.chromium.org",
       "--rietveld_fetch",
       "--upstream",
-      "0fe06637d251d5832f57351f23a63d1cf9458a9d",
+      "1baeb5a8a8ba8145cc2d047ac027a5a5e30ab846",
       "--trybot-json",
       "/path/to/tmp/json",
       "--rietveld_email",
       ""
     ],
     "cwd": "[SLAVE_BUILD]",
     "env": {
       "PRESUBMIT_BUILDER": "1"
     },
     "name": "presubmit",
     "~followup_annotations": [
       "@@@STEP_LOG_LINE@json.output@[@@@",
       "@@@STEP_LOG_LINE@json.output@  []@@@",
       "@@@STEP_LOG_LINE@json.output@]@@@",
       "@@@STEP_LOG_END@json.output@@@"
     ]
   }
 ]