Retry HTTP requests when they fail due to IO errors (#1835)

Closes #1826

Author: nex3

lib/src/http.dart

@@ -228,6 +228,13 @@ final httpClient = new ThrottleClient(
     new _ThrowingClient(new RetryClient(_pubClient,
         retries: 5,
         when: (response) => const [502, 503, 504].contains(response.statusCode),
+        whenError: (error, stackTrace) {
+          if (error is! IOException) return false;
+
+          var chain = new Chain.forTrace(stackTrace);
+          log.io("HTTP error:\n$error\n\n${chain.terse}");
+          return true;
+        },
         delay: (retryCount) {
           if (retryCount < 3) {
             // Retry quickly a couple times in case of a short transient error.

pubspec.yaml

@@ -15,7 +15,7 @@ dependencies:
   glob: "^1.0.0"
   http: "^0.11.0"
   http_multi_server: ">=1.0.0 <3.0.0"
-  http_retry: "^0.1.0"
+  http_retry: "^0.1.1"
   http_throttle: "^1.0.0"
   json_rpc_2: "^2.0.0"
   meta: "^1.1.0"