[SPARK-4169] [Core] Accommodate non-English Locales in unit tests

For me the core tests failed because there are two locale dependent parts in the code.
Look at the Jira ticket for details.

Why is it necessary to check the exception message in isBindCollision in
https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/util/Utils.scala#L1686
?

Author: Niklas Wilcke <1wilcke@informatik.uni-hamburg.de>

Closes #3036 from numbnut/core-test-fix and squashes the following commits:

1fb0d04 [Niklas Wilcke] Fixing locale dependend code and tests

core/src/main/scala/org/apache/spark/util/Utils.scala

@@ -1700,7 +1700,7 @@ private[spark] object Utils extends Logging {
   def isBindCollision(exception: Throwable): Boolean = {
     exception match {
       case e: BindException =>
-        if (e.getMessage != null && e.getMessage.contains("Address already in use")) {
+        if (e.getMessage != null) {
           return true
         }
         isBindCollision(e.getCause)

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

@@ -22,6 +22,8 @@ import scala.util.Random
 import java.io.{File, ByteArrayOutputStream, ByteArrayInputStream, FileOutputStream}
 import java.net.{BindException, ServerSocket, URI}
 import java.nio.{ByteBuffer, ByteOrder}
+import java.text.DecimalFormatSymbols
+import java.util.Locale
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
@@ -103,14 +105,16 @@ class UtilsSuite extends FunSuite {
     val hour = minute * 60
     def str = Utils.msDurationToString(_)
 
+    val sep = new DecimalFormatSymbols(Locale.getDefault()).getDecimalSeparator()
+
     assert(str(123) === "123 ms")
-    assert(str(second) === "1.0 s")
-    assert(str(second + 462) === "1.5 s")
-    assert(str(hour) === "1.00 h")
-    assert(str(minute) === "1.0 m")
-    assert(str(minute + 4 * second + 34) === "1.1 m")
-    assert(str(10 * hour + minute + 4 * second) === "10.02 h")
-    assert(str(10 * hour + 59 * minute + 59 * second + 999) === "11.00 h")
+    assert(str(second) === "1" + sep + "0 s")
+    assert(str(second + 462) === "1" + sep + "5 s")
+    assert(str(hour) === "1" + sep + "00 h")
+    assert(str(minute) === "1" + sep + "0 m")
+    assert(str(minute + 4 * second + 34) === "1" + sep + "1 m")
+    assert(str(10 * hour + minute + 4 * second) === "10" + sep + "02 h")
+    assert(str(10 * hour + 59 * minute + 59 * second + 999) === "11" + sep + "00 h")
   }
 
   test("reading offset bytes of a file") {
@@ -300,12 +304,11 @@ class UtilsSuite extends FunSuite {
     assert(!Utils.isBindCollision(new Exception))
     assert(!Utils.isBindCollision(new Exception(new Exception)))
     assert(!Utils.isBindCollision(new Exception(new BindException)))
-    assert(!Utils.isBindCollision(new Exception(new BindException("Random message"))))
 
     // Positives
-    val be = new BindException("Address already in use")
-    val be1 = new Exception(new BindException("Address already in use"))
-    val be2 = new Exception(new Exception(new BindException("Address already in use")))
+    val be = new BindException("Random Message")
+    val be1 = new Exception(new BindException("Random Message"))
+    val be2 = new Exception(new Exception(new BindException("Random Message")))
     assert(Utils.isBindCollision(be))
     assert(Utils.isBindCollision(be1))
     assert(Utils.isBindCollision(be2))