[blinkpy] Provide a default bucket to git cl try

Since https://crrev.com/c/1779543 , `git cl try` now requires the bucket
name to always be specified. This change sets "luci.chromium.try" as the
default bucket when no bucket is configured in builders.json or passed
to `trigger_try_jobs`.

Change-Id: I5d12625f49f3a57c852abdcbefe641b1eb17d7a6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1783640
Auto-Submit: Robert Ma <robertma@chromium.org>
Reviewed-by: Luke Z <lpz@chromium.org>
Commit-Queue: Robert Ma <robertma@chromium.org>
Cr-Commit-Position: refs/heads/master@{#693195}

third_party/blink/tools/blinkpy/common/config/builders.json

@@ -72,7 +72,6 @@
     "linux-blink-rel": {
         "port_name": "linux-trusty",
         "specifiers": ["Trusty", "Release"],
-        "master": "tryserver.blink",
         "has_webdriver_tests": true,
         "is_try_builder": true
     },

third_party/blink/tools/blinkpy/common/host_mock.py

@@ -94,7 +94,7 @@ class MockHost(MockSystemHost):
                 'is_try_builder': True,
             },
             'android_blink_rel': {
-                'bucket': 'luci.chromium.try',
+                'bucket': 'luci.chromium.android',
                 'port_name': 'android-kitkat',
                 'specifiers': ['KitKat', 'Release'],
                 'is_try_builder': True,

third_party/blink/tools/blinkpy/common/net/git_cl.py

@@ -84,10 +84,9 @@ class GitCL(object):
         # Sort both buckets and builders to ensure stable unit tests.
         for bucket in sorted(builders_by_bucket):
             command = ['try']
-            # Only specify bucket if it's explicitly given to us. Otherwise,
-            # `git cl` will figure out the appropriate bucket.
-            if bucket:
-                command.extend(['-B', bucket])
+            # Buckets are required by `git cl try`. When no bucket is specified,
+            # use the default bucket.
+            command.extend(['-B', bucket or 'luci.chromium.try'])
             for builder in sorted(builders_by_bucket[bucket]):
                 command.extend(['-b', builder])
             self.run(command)

third_party/blink/tools/blinkpy/common/net/git_cl_unittest.py

@@ -47,12 +47,13 @@ class GitCLTest(unittest.TestCase):
         self.assertEqual(host.executive.calls, [
             [
                 'git', 'cl', 'try',
+                '-B', 'luci.chromium.try',
                 '-b', 'fake_blink_try_linux', '-b', 'fake_blink_try_win',
                 '--auth-refresh-token-json', 'token.json'
             ],
             [
                 'git', 'cl', 'try',
-                '-B', 'luci.chromium.try',
+                '-B', 'luci.chromium.android',
                 '-b', 'android_blink_rel',
                 '--auth-refresh-token-json', 'token.json'
             ],
@@ -66,6 +67,7 @@ class GitCLTest(unittest.TestCase):
         self.assertEqual(host.executive.calls, [
             [
                 'git', 'cl', 'try',
+                '-B', 'luci.chromium.try',
                 '-b', 'fake_blink_try_linux', '-b', 'fake_blink_try_win',
                 '--auth-refresh-token-json', 'token.json'
             ],