Description of problem: 

In ssl3con.c there are two duplicates entries in this table
/* must use ssl_LookupCipherSuiteDef to access */
static const ssl3CipherSuiteDef cipher_suite_defs[] = ...
....
    {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_rsa},
    {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_ecdsa},
    {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_rsa, prf_256},
    {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_ecdsa, prf_256},
....

Notice that first and second entries match third and fourth, respectively, but are missing the last field. 

Version-Release number of selected component (if applicable): nss-3.21.1-6 and was already present on nss-3.19.1-19.el7_2

How reproducible: Always

Steps to Reproduce: 
I'll copy from https://bugzilla.redhat.com/show_bug.cgi?id=1310581#c12
where it was originally reported


I have found spurious, duplacate, entries in the cipher_suite_defs[] array.

$ cd nss-3.21.0/nss/lib/ssl/

$ grep -c "{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_" ssl3con.c
2 

$ grep "{TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_" ssl3con.c
    {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_rsa},
    {TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_rsa, prf_256},

The second is correct.

$ grep -c "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_" ssl3con.c
2

[emaldona@dhcp-16-216 ssl]$ grep "TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_" ssl3con.c
    {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_ecdsa},
    {TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256, cipher_aes_128_gcm, mac_aead, kea_ecdhe_ecdsa, prf_256},

The second is correct.

In each case the first is missing the last field. 

Additional info: 

Though the flaw hasn't caused  problems yet, having entries with an uninitialized prf has the potential for random failures. 

The fix https://bugzilla.redhat.com/attachment.cgi?id=1143400
has been reviewed, approved, committed, and build as nss-3.21.0-7.el7_2
https://brewweb.engineering.redhat.com/brew/buildinfo?buildID=488608