integration: add some tests for bind mount over a dangling symlink

[lifubang]

No description provided.

[cyphar]

"on" is the wrong word to use here, "through" is probably better. ("on" to me means that the bind-mount is on top of the dangling symlink, which isn't the case.)

Your tests here all use .. but that isn't actually an example nor root cause of the dangling symlink issues we had reported to us when I added 3f92552 (it would be nice to reference that commit as well). It would be nice to have a test with a symlink to /foo/bar/baz/a/b/c/d/e/f (and a relative version too), both of which would cause issues without ...

I would also check cat /proc/self/mounts (or at least look at the inode number with stat) to confirm it is actually a bind-mount in the test.

Did you want me to carry this in #4985 instead? (I was going to write tests there as well.)

[lifubang]

Did you want me to carry this in #4985 instead? (I was going to write tests there as well.)

Yes

[cyphar]

Carried in #4985.