Allow IOExceptions with null messages to propogate.

I noticed that one of the exceptions that causes #2470 is
SocketTimeoutException. The outer exception handlers of
HttpConnector.connect have logic to handle such an exception, so just
let them propagate.

Change-Id: Ic87b678431178e296f14f1be34acf8024ddbfc19
PiperOrigin-RevId: 163732268

1 files changed, 4 insertions, 7 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/HttpConnector.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/HttpConnector.java
index f2c6535326..dacd93ae08 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/HttpConnector.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/downloader/HttpConnector.java
@@ -121,13 +121,10 @@ class HttpConnector {
           // This will happen if the user does something like specify a port greater than 2^16-1.
           throw new UnrecoverableHttpException(e.getMessage());
         } catch (IOException e) {
-          // I'm not sure in what cases this happens, but IOException can be thrown with a null
-          // message.
-          if (e.getMessage() == null) {
-            throw new UnrecoverableHttpException(
-                "Failed to even get an error message from " + url);
-          }
-          if (!e.getMessage().startsWith("Server returned")) {
+          // Some HTTP error status codes are converted to IOExceptions, which we can only
+          // disambiguate from other IOExceptions by checking the exception message. We need to be
+          // careful because some exceptions (e.g., SocketTimeoutException) may have a null message.
+          if (e.getMessage() == null || !e.getMessage().startsWith("Server returned")) {
             throw e;
           }
           code = connection.getResponseCode();