gistfile1

diff --git a/core/src/main/java/org/jruby/Ruby.java b/core/src/main/java/org/jruby/Ruby.java
index 1d12ac0..4ede395 100644
--- a/core/src/main/java/org/jruby/Ruby.java
+++ b/core/src/main/java/org/jruby/Ruby.java
@@ -2706,6 +2706,7 @@ public final class Ruby {
         }
 
         PrintStream errorStream = getErrorStream();
+        errorStream.println("Unhandled exception in thread " + Thread.currentThread().getName() + ":");
         errorStream.print(config.getTraceType().printBacktrace(excp, errorStream == System.err && getPosix().isatty(FileDescriptor.err)));
     }
     
diff --git a/core/src/main/java/org/jruby/RubyThread.java b/core/src/main/java/org/jruby/RubyThread.java
index d03135e..e6c89f2 100644
--- a/core/src/main/java/org/jruby/RubyThread.java
+++ b/core/src/main/java/org/jruby/RubyThread.java
@@ -1178,7 +1178,8 @@ public class RubyThread extends RubyObject implements ExecutionContext {
 
             runtime.getThreadService().getMainThread().raise(new IRubyObject[] {systemExit}, Block.NULL_BLOCK);
             return;
-        } else if (runtime.getDebug().isTrue()) {
+        } else {
+            // mri-6647: log something for raised exceptions when not aborting
             runtime.printError(exception.getException());
         }
         exitingException = exception;