run_tests: fix cat and avoid using another external tool

run_tests

@@ -74,7 +74,7 @@
       tests_errors=0
   fi
   import_errors=$(grep -P 'o(penerp|doo).(modules.module|[^ ]+): Can not `import [a-z0-9_]+`.' $logfile)
-  import_errors_number=$(cat $import_errors|wc -l)
+  import_errors_number=$(grep -P 'o(penerp|doo).(modules.module|[^ ]+): Can not `import [a-z0-9_]+`.' $logfile -c)
   if [[ "$import_errors_number" -ne 0 ]];
   then
       test_errors=$((test_errors+import_errors_number))
@@ -133,7 +133,7 @@
     GREP_COLOR='0;31' grep --color=always "ERROR \([[:alnum:]]\|_\)* .\+\.test_.\+ ERROR:" $logfile
     if [[ -n "$import_errors" ]];
     then
-        echo $import_errors
+        echo "$import_errors"
     fi
 fi