`x.py test mir-opt --bless` does not bless some tests

[RalfJung]

To reproduce, simply edit the file tests/mir-opt/pre-codegen/checked_ops.checked_shl.PreCodegen.after.mir and then run x.py test mir-opt --bless. I'd expect the file to be changed back, but actually it is left unchanged.

Interestingly, x.py test mir-opt does check that file. This is on a x86-64 host, and the test is marked needs-unwind and only-x86_64. --bless adds a bunch of extra targets to bless, seems like my default target x86_64 with unwinding is not one of them though?

--bless should make sure to always bless the configuration that is tested without --bless.

[Nadrieril]

--bless should make sure to always bless the configuration that is tested without --bless.

That's resolved by #122257. It does not however resolve your issue