Bug 1784179 - Don't stop at the first error during CI builds. r=firefox-build-system-reviewers,nalexander

It can be a frustrating experience to push something to e.g. try, get
build errors, fix them, and realize on a subsequent push that there were
other build errors, but since the build failed as soon as it reached the
first error, the logs didn't show them.

While stopping at the first error locally is more helpful locally
(although it still stop immediately and errors are often buried in the
logs), it is actually desirable to avoid stopping on automation.

Differential Revision: https://phabricator.services.mozilla.com/D154327

client.mk

@@ -61,9 +61,7 @@ endif
 ### Build it
 build::
 	+$(MOZ_MAKE) $(SCCACHE_STOP_ON_FAILURE)
-
 ifdef MOZ_AUTOMATION
-build::
 	+$(MOZ_MAKE) automation/build $(SCCACHE_STOP_ON_FAILURE)
 endif
 

python/mozbuild/mozbuild/build_commands.py

@@ -160,6 +160,9 @@ def build(
     doing_pgo = configure_args and "MOZ_PGO=1" in configure_args
     # Force verbosity on automation.
     verbose = verbose or bool(os.environ.get("MOZ_AUTOMATION", False))
+    # Keep going by default on automation so that we exhaust as many errors as
+    # possible.
+    keep_going = keep_going or bool(os.environ.get("MOZ_AUTOMATION", False))
     append_env = None
 
     # By setting the current process's priority, by default our child processes