Keep sending want lines if the server doesn't anwer a flush

Some servers take a long time to answer and expect us to keep sending
want lines; otherwise they close the connection. Avoid this by waiting
for one second for the server to answer. If the timeout runs out,
treat is as a NAK and keep sending want lines.

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

src/transport_git.c

@@ -23,6 +23,8 @@
  * Boston, MA 02110-1301, USA.
  */
 
+#include <sys/select.h>
+
 #include "git2/net.h"
 #include "git2/common.h"
 #include "git2/types.h"
@@ -388,6 +390,27 @@ static int git_negotiate_fetch(git_transport *transport, git_repository *repo, g
 			git_pkt *pkt;
 			git_pkt_send_flush(t->socket);
 			while (1) {
+				fd_set fds;
+				struct timeval tv;
+
+				FD_ZERO(&fds);
+				FD_SET(t->socket, &fds);
+				tv.tv_sec = 1; /* Wait for max. 1 second */
+				tv.tv_usec = 0;
+
+				/* The select(2) interface is silly */
+				error = select(t->socket + 1, &fds, NULL, NULL, &tv);
+				if (error < GIT_SUCCESS) {
+					error = git__throw(GIT_EOSERR, "Error in select");
+				} else if (error == 0) {
+				/*
+				 * Some servers don't respond immediately, so if this
+				 * happens, we keep sending information until it
+				 * answers.
+				 */
+					break;
+				}
+
 				error = gitno_recv(&buf);
 				if (error < GIT_SUCCESS) {
 				  error = git__rethrow(error, "Error receiving data");