Restore stress_test_common script.

courgette/stress_test_common

Index: courgette/stress_test_common
diff --git a/courgette/stress_test_common b/courgette/stress_test_common
new file mode 100755
index 0000000000000000000000000000000000000000..b6c9b25e8886567cda17bba240ef7337a3cce611
--- /dev/null
+++ b/courgette/stress_test_common
@@ -0,0 +1,16 @@
+#!/bin/bash
+
+# Emit an error message
+error() {
+  echo "error: ${@}" >&2
+}
+
+# Given a token, search for and count the instances of lines from the
+# logfile that start with the token.
+count_result() {
+  if [ ! -z "${1}" ]; then
+    echo $(cat "${log}" | grep "^${1} " | wc -l)    
+  else
+    echo 0
+  fi
+}