fix(updating)!: do not run tasks after project update

Running tasks after an update mixes concerns with post-copy tasks and
post-update migration tasks.

BREAKING CHANGE: Copier no longer runs tasks after updating a project.
Use post-update migration tasks instead.

Author: sisp

copier/_main.py

@@ -1548,10 +1548,6 @@ def _apply_update(self) -> None:  # noqa: C901
                             subproject_subdir / self.answers_relpath,
                         )
 
-        if not self.skip_tasks:
-            with Phase.use(Phase.TASKS):
-                self._execute_tasks(self.template.tasks)
-
         # Run post-migration tasks.
         with Phase.use(Phase.MIGRATE):
             self._execute_tasks(

docs/updating.md

@@ -132,7 +132,7 @@ project_half("half migrated<br>project")
 project_updated("updated project")
 project_full("fully updated<br>and migrated project")
 
-update["3-way merge<br>& run tasks again"]
+update["3-way merge"]
 regen_current["generate and run tasks"]
 regen_latest["generate and run tasks"]
 

tests/test_legacy_migration.py

@@ -79,7 +79,7 @@ def test_migrations_and_tasks(tmp_path: Path, skip_tasks: bool) -> None:
         assert not (dst / "created-with-tasks.txt").exists()
         assert (dst / "delete-in-tasks.txt").exists()
     else:
-        assert (dst / "created-with-tasks.txt").read_text() == "task 1\ntask 2\n" * 2
+        assert (dst / "created-with-tasks.txt").read_text() == "task 1\ntask 2\n"
         assert not (dst / "delete-in-tasks.txt").exists()
     assert not (dst / "delete-in-migration-v2.txt").exists()
     assert not (dst / "migrations.py").exists()