Use latest 2.1 version of sprockets-rails
Merge pull request #16649 from Agis-/pg-columns-for-distinct

Fix postgresql adapter #columns_for_distinct trimming whitespace it shouldn't
CHANGELOG & improvements to #16649

* Require either FIRST or LAST qualifier for "NULLS ..."
* Require whitespace before "NULLS ..."
Merge pull request #16664 from rubys/4-1-stable

Use latest 2.1 version of sprockets-rails
Clarify that unknown keys will become HTML attrs

Docs for all the other form tag helpers in this
file already clarify this.

[ci skip]
Remove erroneous form_tag option docs

This is true of the first param (url_for_options),
not of the second options param which is being
documented here.

[ci skip]
Merge pull request #16693 from tjschuck/form_for_doc_options_4-1

Backport: documentation update for form_for options
Fix setting a polymorphic association's attributes to nil and saving, if that association had been non-nil and loaded.

This raised a nil deref, because the stale_state test returned true (the target was no longer valid) and so #find_target called #scope, which ran klass.all - which failed because #klass is now nil.

This only happened if saving the record holding this polymorphic association, as opposed to say referencing the association, because the latter is implemented by the SingularAssociation#reader method which called #reload if the target was stale.  This patch does something similar, but a bit less radical (calling reset).