Nit fixes

Author: Ilya Ganelin

core/src/test/scala/org/apache/spark/util/UtilsSuite.scala

@@ -174,17 +174,10 @@ class UtilsSuite extends FunSuite with ResetSystemProperties {
     intercept[NumberFormatException] {
       Utils.byteStringAsBytes("600gb This breaks")
     }
-
+    
     intercept[NumberFormatException] {
       Utils.byteStringAsBytes("This 123mb breaks")
     }
-    
-//    // Test overflow
-//    intercept[NumberFormatException] {
-//      
-//
-//      ByteUnit.convertTo(0x7fffffffffffffffL, ByteUnit.KiB)
-//    }
   }
 
   test("bytesToString") {

network/common/src/main/java/org/apache/spark/network/util/ByteUnit.java

@@ -39,8 +39,8 @@ public long convertTo(long d, ByteUnit u) {
     if (multiplier > u.multiplier) {
       long ratio = multiplier / u.multiplier;
       if (Long.MAX_VALUE / ratio < d) {
-        throw new IllegalArgumentException("Conversion of" + d + "exceeds Long.MAX_VALUE in "
-          + name() + ". Try a larger suffix (e.g. MiB instead of KiB)");
+        throw new IllegalArgumentException("Conversion of " + d + " exceeds Long.MAX_VALUE in "
+          + name() + ". Try a larger unit (e.g. MiB instead of KiB)");
       }
       return d * ratio;
     } else {