Backport PR #40994: REGR: memory_map with non-UTF8 encoding

[twoertwein]

Backport PR #40994

[twoertwein]

I think this PR depends on some not-backported PRs?

[jreback]

this might be non-trival to make work. ping when / if ready.

[twoertwein]

I will not have time to look into this for the next ~two weeks. The whatsnew entry should probably be moved to 1.3.

[phofl]

This makes this compatible with the logic on master

[simonjayhawkins]

The whatsnew entry should probably be moved to 1.3.

this fixed a regression in 1.2 #40986 (comment), so would be good to backport.

The changes do no look trivial which would normally be desirable for a backport.

@twoertwein @phofl @jreback happy to merge this?

[phofl]

I think the only change is

            errors = self.errors if self.errors is not None else "strict"

which is necessary because we have a new keyword on master setting this flag.

[simonjayhawkins]

Thanks @twoertwein @phofl