bisect-kit: fixup ssh workaround

BUG=None
TEST=run eval_cros_autotest.py manually

Change-Id: Ib18fe621b4d2d025b9467972267132faa1cbda9c
Reviewed-on: https://chromium-review.googlesource.com/1506332
Commit-Ready: Kuang-che Wu <kcwu@chromium.org>
Tested-by: Kuang-che Wu <kcwu@chromium.org>
Reviewed-by: Chi-Ngai Wan <cnwan@google.com>
diff --git a/eval_cros_autotest.py b/eval_cros_autotest.py
index 387408c..2aa934d 100755
--- a/eval_cros_autotest.py
+++ b/eval_cros_autotest.py
@@ -189,8 +189,10 @@
   # TODO(kcwu): remove this workaround once we no longer support bisecting
   # versions earlier than R73-11445.0.0.
   ssh_path = os.path.join(opts.chromeos_root, 'chroot/usr/bin/ssh')
-  if 'file descriptor passing not supported' in open(ssh_path).read():
-    cros_util.cros_sdk(opts.chromeos_root, 'sudo', 'emerge', 'net-misc/openssh')
+  if os.path.exists(ssh_path):
+    if 'file descriptor passing not supported' in open(ssh_path).read():
+      cros_util.cros_sdk(opts.chromeos_root, 'sudo', 'emerge',
+                         'net-misc/openssh')
 
   if opts.reinstall:
     util.ssh_cmd(opts.dut, 'rm', '-rf', '/usr/local/autotest')