upload_symbols: Add logging to ensure retries

We're seeing some random failures with uploads that are causing the
stage to fail, even though these types of errors should be retried.  Our
current approach provides no longing on retries therefore I want to
ensure that we're seeing retries before failing.  With multiple retries,
on a timeout, we should rarely see failures.

BUG=chromium:956599
TEST='cros_sdk -- /mnt/host/source/chromite/run_tests'

Change-Id: Ic9c0af2b943eba4c9cdf7e7e948d165556c68bcc
Reviewed-on: https://chromium-review.googlesource.com/1586183
Commit-Ready: Mike Nichols <mikenichols@chromium.org>
Tested-by: Mike Nichols <mikenichols@chromium.org>
Reviewed-by: Jason Clinton <jclinton@chromium.org>
diff --git a/scripts/upload_symbols.py b/scripts/upload_symbols.py
index 9953fdc..0a55ca4 100644
--- a/scripts/upload_symbols.py
+++ b/scripts/upload_symbols.py
@@ -438,9 +438,12 @@
         # This command retries the upload multiple times with growing delays. We
         # only consider the upload a failure if these retries fail.
         def ShouldRetryUpload(exception):
-          return isinstance(exception, (requests.exceptions.RequestException,
-                                        urllib2.URLError,
-                                        httplib.HTTPException, socket.error))
+          if isinstance(exception, (requests.exceptions.RequestException,
+                                    urllib2.URLError,
+                                    httplib.HTTPException, socket.error)):
+            logging.info('Request failed, retrying: %s', exception)
+            return True
+          return False
 
         with cros_build_lib.TimedSection() as timer:
           retry_stats.RetryWithStats(