BUG/MINOR: ssl: allow duplicate certificates in ca-file directories

It looks like OpenSSL 1.0.2 returns an error when trying to insert a
certificate whis is already present in a X509_STORE.

This patch simply ignores the X509_R_CERT_ALREADY_IN_HASH_TABLE error if
emitted.

Should fix part of issue #1780.

Must be backported in 2.6.
1 file changed