Bugzilla

Since https://hg.mozilla.org/mozilla-unified/rev/b7380df3b9a8ca43204527dfe9f851ab39b00d3c, pushes to try (with try_task_config) run all tasks that set `always_target`, whereas previously they only ran when the relevant files changed.

As I understand it, this is because:
- `try_task_config` sets the `optimize_target_tasks` parameter to `False` (https://searchfox.org/mozilla-central/rev/0a2eba79c24300ce0539f91c1bebac2e75264e58/taskcluster/gecko_taskgraph/decision.py#495) to prevent optimizing out tasks the user explicitly requested
- when `optimize_target_tasks` is false, when generating the graph we add the target task set to `do_not_optimize`
- tasks in `do_not_optimize` run can't be optimized out, including using their `when.files-changed` setting
- since the patch referenced above, the target task set contains not only the tasks that the user explicitly requested, but also those with `always_target` enabled.

Since https://hg.mozilla.org/mozilla-unified/rev/b7380df3b9a8ca43204527dfe9f851ab39b00d3c, pushes to try (with try_task_config) run all tasks that set `always_target`, whereas previously they only ran when the relevant files changed.

As I understand it, this is because:
- `try_task_config` sets the `optimize_target_tasks` parameter to `False` (https://searchfox.org/mozilla-central/rev/0a2eba79c24300ce0539f91c1bebac2e75264e58/taskcluster/gecko_taskgraph/decision.py#495) to prevent optimizing out tasks the user explicitly requested
- when `optimize_target_tasks` is false, when generating the graph we add the target task set to `do_not_optimize` (https://searchfox.org/mozilla-central/rev/0a2eba79c24300ce0539f91c1bebac2e75264e58/taskcluster/gecko_taskgraph/generator.py#374)
- tasks in `do_not_optimize` run can't be optimized out, including using their `when.files-changed` setting (https://searchfox.org/mozilla-central/rev/0a2eba79c24300ce0539f91c1bebac2e75264e58/third_party/python/taskcluster_taskgraph/taskgraph/optimize/base.py#196-199)
- since the patch referenced above, the target task set contains not only the tasks that the user explicitly requested, but also those with `always_target` enabled.