tar: reject/prefix_dot_name_foo_reg is arguably valid

[woodruffw]

prefix_dot_name_foo_reg is currently marked as "reject," but it's arguably fine: pax doesn't forbid . in the ustar prefix field, and ./foo is safely normalizable to foo within the destination dir/extraction root.

(Seems marginal though, I'm curious if you have a different opinion!)

[woodruffw]

Ref:

malo/tar/gen.py

Lines 698 to 703 in 3df544f

	# reject/prefix_dot_name_foo_reg.tar: prefix is '.', name is 'foo', regular file
	gen(
	"reject/prefix_dot_name_foo_reg.tar",
	entry(TarHeader(name=b"foo", prefix=b".", typeflag=b"0"))
	+ end_of_archive(),
	)

[thatch]

Hmm yes, I don't have any argument for keeping it in "reject" -- how about demoting both this and the directory one above it to "iffy" (since the intent is not ambiguous, but the interpretation has some gotchas)

[woodruffw]

Seems reasonable!

(I think the "regular file that ends with slash" one could also be kept in reject, AFAICT only pre-ustar tar used that idiom and pax/GNU parsers will vary in how they treat it.)

[thatch]

Kind of related, one of the oddities I ran across is this error message along the same lines as this whole project is.