Add CURLE_SEND_ERROR and CURLE_RECV_ERROR to the set of retryable errors.

Data problems after connections are established should be retried as well.
Extend to appropriate libcurl codes.  Also allow our connectivity to drop
to as low as a single connection when trying to recover.

indra/llcorehttp/_httppolicy.cpp

@@ -46,7 +46,7 @@ struct HttpPolicy::State
 	State()
 		: mConnMax(DEFAULT_CONNECTIONS),
 		  mConnAt(DEFAULT_CONNECTIONS),
-		  mConnMin(2),
+		  mConnMin(1),
 		  mNextSample(0),
 		  mErrorCount(0),
 		  mErrorFactor(0)
@@ -303,6 +303,8 @@ bool HttpPolicy::stageAfterCompletion(HttpOpRequest * op)
 	static const HttpStatus cant_connect(HttpStatus::EXT_CURL_EASY, CURLE_COULDNT_CONNECT);
 	static const HttpStatus cant_res_proxy(HttpStatus::EXT_CURL_EASY, CURLE_COULDNT_RESOLVE_PROXY);
 	static const HttpStatus cant_res_host(HttpStatus::EXT_CURL_EASY, CURLE_COULDNT_RESOLVE_HOST);
+	static const HttpStatus send_error(HttpStatus::EXT_CURL_EASY, CURLE_SEND_ERROR);
+	static const HttpStatus recv_error(HttpStatus::EXT_CURL_EASY, CURLE_RECV_ERROR);
 
 	// Retry or finalize
 	if (! op->mStatus)
@@ -313,7 +315,9 @@ bool HttpPolicy::stageAfterCompletion(HttpOpRequest * op)
 			((op->mStatus.isHttpStatus() && op->mStatus.mType >= 499 && op->mStatus.mType <= 599) ||
 			 cant_connect == op->mStatus ||
 			 cant_res_proxy == op->mStatus ||
-			 cant_res_host == op->mStatus))
+			 cant_res_host == op->mStatus ||
+			 send_error == op->mStatus ||
+			 recv_error == op->mStatus))
 		{
 			// Okay, worth a retry.  We include 499 in this test as
 			// it's the old 'who knows?' error from many grid services...