largefiles: make cat on standins do something
cat of a standin would silently fail.
The use of standins is mostly an implementation detail, but it is already a bit
leaking. Being able to see the content of standins might be convenient for
debugging.
$ hg init a
$ cd a
$ hg init b
$ echo x > b/x
Should print nothing:
$ hg add b
$ hg st
$ echo y > b/y
$ hg st
Should fail:
$ hg st b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
$ hg add b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
Should fail:
$ hg add b b/x
abort: path 'b/x' is inside nested repo 'b' (glob)
[255]
$ hg st
Should arguably print nothing:
$ hg st b
$ echo a > a
$ hg ci -Ama a
Should fail:
$ hg mv a b
abort: path 'b/a' is inside nested repo 'b' (glob)
[255]
$ hg st
$ cd ..