Restore compatibility with GOST2001 implementations.

Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7985)

(cherry picked from commit 673e0bbbe4b9cbd19a247c0b18c171bb0421915a)

ssl/statem/extensions.c

@@ -623,7 +623,12 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
                 && type != TLSEXT_TYPE_cookie
                 && type != TLSEXT_TYPE_renegotiate
                 && type != TLSEXT_TYPE_signed_certificate_timestamp
-                && (s->ext.extflags[idx] & SSL_EXT_FLAG_SENT) == 0) {
+                && (s->ext.extflags[idx] & SSL_EXT_FLAG_SENT) == 0
+#ifndef OPENSSL_NO_GOST
+                && !((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0
+                     && type == TLSEXT_TYPE_cryptopro_bug)
+#endif
+								) {
             SSLfatal(s, SSL_AD_UNSUPPORTED_EXTENSION,
                      SSL_F_TLS_COLLECT_EXTENSIONS, SSL_R_UNSOLICITED_EXTENSION);
             goto err;