better handling of error logs for wml unit test script

error logs get pooled in errors.log
This is necessary because we don't stop testing when we get an
error anymore.

run_wml_tests

@@ -108,8 +108,16 @@ run_test()
   wesnoth -u $2 $opts 2> error.log
   if check_errs $2 $? $1; then 
     FirstTest=0 #Don't start using validcache flag until at least one test has passed without error
+    rm error.log
     return 0
   else
+    if [ -f "errors.log" ]; then
+      echo -e "\n--- next unit test ---\n" >> errors.log
+      cat error.log >> errors.log
+    else
+      cp error.log errors.log
+    fi
+    rm error.log
     return 1
   fi
 }
@@ -133,8 +141,16 @@ run_test_unix_timeout()
   timeout "--kill-after=$timer1" $timer wesnoth -u $2 $opts 2> error.log
   if check_errs $2 $? $1; then 
     FirstTest=0 #Don't start using validcache flag until at least one test has passed without error
+    rm error.log
     return 0
   else
+    if [ -f "errors.log" ]; then
+      echo -e "\n--- next unit test ---\n" >> errors.log
+      cat error.log >> errors.log
+    else
+      cp error.log errors.log
+    fi
+    rm error.log
     return 1
   fi
 }
@@ -194,6 +210,10 @@ done
 
 echo "Running" $TESTS "test scenarios."
 
+if [ -f "errors.log" ]; then
+  rm errors.log
+fi
+
 AllPassed=1
 FirstTest=1
 
@@ -226,6 +246,7 @@ done
 
 if [ $AllPassed -eq 0 ]; then
   echo "Not all tests gave the correct result."
+  echo "Check errors.log for error reports."
   exit 1
 else
   echo "All tests gave the correct result."