Allow SSH agent errors to surface.

This will allow users to know when their sessions dies because of
a non-functioning agent / stale environment variables.

BUG=None
TEST=Script emits an error message to stderr when ssh-add fails.

Change-Id: Ia1c7a642eb75a256e69730c6095ace09284558a2
Reviewed-on: https://gerrit.chromium.org/gerrit/31621
Reviewed-by: Chris Sosa <sosa@chromium.org>
Commit-Ready: Gilad Arnold <garnold@chromium.org>
Tested-by: Gilad Arnold <garnold@chromium.org>
diff --git a/run_remote_tests.sh b/run_remote_tests.sh
index 89c8c2d..7410ee1 100755
--- a/run_remote_tests.sh
+++ b/run_remote_tests.sh
@@ -357,7 +357,7 @@
 
   remote_access_init
   # autotest requires that an ssh-agent already be running
-  start_ssh_agent >/dev/null 2>&1
+  start_ssh_agent >/dev/null
 
   learn_board
   if [[ -n "${FLAGS_autotest_dir}" ]]; then