Simplify GetAllCredentials
Simplify GetAllCredentials

In the exec.ErrNotFound case, set creds to nil
so that we have the ordinary handling on the main
line.

Then eliminate two consecutive if statements with the same
condition.

Signed-off-by: Miloslav Trmač <9c008e38982a5397deb855345fb164f0558459ae@redhat.com>

containers/image,containers/image