TLSv1.3 session are lost after a graceful restart, which isn't the case with TLSv1.2.

Steps to reproduce:
- Configure shared-memory session cache:
    SSLSessionCache shmcb:/path/to/datafile[(size)] 

- connect with openssl s_client with the -sess_out <file> parameter so that we get a session file.

- gracefully restart apache

- connect again with openssl s_client, this time with the -sess_in <file> parameter so we use that session from before.

- see the full-handshake happening...

now to see the difference just do the same steps but don't gracefully restart apache.

i have had a look in the sources at ssl_scache.c and the killing respectively the re-initialization of the cache is skipped correctly:

at the top of ssl_scache_init: 
    if (ap_is_graceful()) {
        return APR_SUCCESS;
    }

and also at the beginning of ssl_scache_kill:
    if (mc->sesscache && !ap_is_graceful()) {
        mc->sesscache->destroy(mc->sesscache_context, s);
    }


but still something must be wrong because the graceful obviously somehow destroys the session...

for more details also see my question on stackoverflow:
https://stackoverflow.com/questions/60080365/apaches-sslsessioncache-not-working-correctly-with-tlsv1-3-and-graceful-restart