Make findRuntimeRoots() more resilient to disappearing processes

I saw this random failure in https://hydra.nixos.org/build/211811692:

  error: opening /proc/15307/fd: No such process

while running nix-collect-garbage in a readfile-context.sh. This is
because we're not handling ESRCH errors reading /proc/<pid>/fd. So
just move the read inside the try/catch where we do handle it.

0 files changed, 0 insertions, 0 deletions