Fix test failing on Windows because of line feed assumption

The line separator length was assumed to be 1 byte wide, although it
could be 2 on some platforms (aka Windows).

core/src/test/java/hudson/model/RunTest.java

@@ -189,7 +189,8 @@ public class RunTest {
         for (int i = 1; i < 10; i++) {
             assertEquals("dummy" + (10+i), logLines.get(i));
         }
-        assertEquals("[...truncated 68 B...]", logLines.get(0));
+        int truncatedCount = 10* ("dummyN".length() + System.getProperty("line.separator").length()) - 2;
+        assertEquals("[...truncated "+truncatedCount+" B...]", logLines.get(0));
     }
 
     @Test