[smoltafet]

Fixes #478 and #469.

#478 — doit forget crashes when no default_tasks are configured. With no task names on the command line and no default_tasks, Forget._execute iterated over self.sel_tasks, which is None in that case, raising TypeError: 'NoneType' object is not iterable. run and clean already treat "nothing selected" as "all tasks" (clean checks sel_tasks is not None explicitly), so forget now does the same: it forgets every task. The collected list is de-duplicated, since a list built from all tasks contains group subtasks twice (once directly, once via the group), and dependencies shared by several selected tasks would otherwise be forgotten (and reported) repeatedly.

#469 — default_tasks set via config file / DoitMain(extra_config=...) was ignored by forget. default_tasks is not a registered command option, so values in DoitMain's config (extra_config or INI/TOML files, both available as self.config_vals) were silently dropped by the option parser; only DOIT_CONFIG in the dodo file reached params, because execute() merges it wholesale. DoitCmdBase.execute now registers a config-supplied default_tasks as a default value before merging DOIT_CONFIG, which keeps the existing precedence (DOIT_CONFIG wins, as it does for regular options).

Tests: 4 new tests in tests/test_cmd_forget.py — unit tests for the no-selection case (plain and --follow-sub) and end-to-end tests through DoitMain for both issues. All 4 fail on the unmodified code. Full suite: 839 passed, with the same single pre-existing environment failure as on master (tests/test___main__.py::TestMain::test_execute, also failing without this change).

[smoltafet]

Hi @schettino72, could you take a look at this when you have a moment? Happy to fix up anything that needs changing. Thanks!