Actual fix... :)

Author: cowtowncoder

ion/src/main/java/com/fasterxml/jackson/dataformat/ion/IonParser.java

@@ -413,8 +413,8 @@ private long _getLongValue() throws IOException {
         try {
             if (this.getNumberType() == NumberType.BIG_INTEGER) {
                 BigInteger bigInteger = _reader.bigIntegerValue();
-                if (BI_MIN_INT.compareTo(bigInteger) > 0 || BI_MAX_INT.compareTo(bigInteger) < 0) {
-                    this.reportOverflowLong();
+                if (BI_MIN_LONG.compareTo(bigInteger) > 0 || BI_MAX_LONG.compareTo(bigInteger) < 0) {
+                    reportOverflowLong();
                 }
                 return bigInteger.longValue();
             } else {

ion/src/test/java/com/fasterxml/jackson/dataformat/ion/IonNumberOverflowTest.java

@@ -78,7 +78,7 @@ private void _testLongCoercionFail(BigInteger input) throws Exception
     @Test
     public void testLongAsBigIntegerSize() throws Exception {
         // Note: Values: Long.MAX_VALUE through Long.MAX_VALUE -7 are considered LONG by Ion.  
-        BigInteger bigIntLongValue = new BigInteger(Long.MAX_VALUE + "").subtract(new BigInteger("10"));
+        BigInteger bigIntLongValue = new BigInteger(Long.MAX_VALUE + "").subtract(BigInteger.TEN);
         IonParser bigIntLongParser = (IonParser) new IonFactory().createParser(bigIntLongValue.toString());
         assertEquals(JsonToken.VALUE_NUMBER_INT, bigIntLongParser.nextToken());
         assertEquals(JsonParser.NumberType.BIG_INTEGER, bigIntLongParser.getNumberType());