send-email: set SSL options through IO::Socket::SSL::set_client_defaults

When --smtp-encryption=ssl, we use a Net::SMTP::SSL connection,
passing its ->new all the options that would otherwise go to
Net::SMTP->new (most options) and IO::Socket::SSL->start_SSL (for the
SSL options).

However, while Net::SMTP::SSL replaces the underlying socket class
with an SSL socket, it does nothing to allow passing options to that
socket.  So the SSL-relevant options are lost.

Fortunately there is an escape hatch: we can directly set the options
with IO::Socket::SSL::set_client_defaults.  They will then persist
within the IO::Socket::SSL module.

Signed-off-by: Thomas Rast <tr@thomasrast.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-send-email.perl

@@ -1214,11 +1214,14 @@ X-Mailer: git-send-email $gitversion
 			$smtp_server_port ||= 465; # ssmtp
 			require Net::SMTP::SSL;
 			$smtp_domain ||= maildomain();
+			require IO::Socket::SSL;
+			# Net::SMTP::SSL->new() does not forward any SSL options
+			IO::Socket::SSL::set_client_defaults(
+				ssl_verify_params());
 			$smtp ||= Net::SMTP::SSL->new($smtp_server,
 						      Hello => $smtp_domain,
 						      Port => $smtp_server_port,
-						      Debug => $debug_net_smtp,
-						      ssl_verify_params());
+						      Debug => $debug_net_smtp);
 		}
 		else {
 			require Net::SMTP;