Fix log syntax.

And add better error message when instrumentation test is not
present.

Change-Id: I381421e59a3b667a5c3090ccd49e38fe99d680c5
diff --git a/testrunner/runtest.py b/testrunner/runtest.py
index 9082d79..1c11e27 100755
--- a/testrunner/runtest.py
+++ b/testrunner/runtest.py
@@ -294,7 +294,7 @@
     if m:
       remote_path = m.group(1)
       abs_install_path = os.path.join(self._root_path, install_path)
-      logger.Log("adb push %s %s", abs_install_path, remote_path)
+      logger.Log("adb push %s %s" % (abs_install_path, remote_path))
       self._adb.Push(abs_install_path, remote_path)
     else:
       logger.Log("Error: Failed to recognize path of file to install %s" % install_path)