Auto merge of #35885 - durka:gh35753, r=arielb1
Auto merge of #35885 - durka:gh35753, r=arielb1

modify fds-are-cloexec test to open a file that exists

Fixes #35753.

Is it a valid assumption that the current directory is always the root of the repo when the tests are run?

r? @nagisa

GBGamer/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust