BUG/MINOR: ssl: Do not look for key in extra files if already in pem

A bug was introduced by commit 9bf3a1f67eb3bc6f02abcabf8ab141840c7a1db2
"BUG/MINOR: ssl: Fix crash when no private key is found in pem".
If a private key is already contained in a pem file, we will still look
for a .key file and load its private key if it exists when we should
not.

This patch should be backported to all branches where the original fix
was backported (all the way to 2.2).
1 file changed