Fixes #835 new change to reduce spinning on connection return

when the pool is saturated.

src/main/java/com/zaxxer/hikari/util/ConcurrentBag.java

@@ -123,15 +123,13 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
    public T borrow(long timeout, final TimeUnit timeUnit) throws InterruptedException
    {
       // Try the thread-local list first
-      if (waiters.get() == 0) {
-         final List<Object> list = threadList.get();
-         for (int i = list.size() - 1; i >= 0; i--) {
-            final Object entry = list.remove(i);
-            @SuppressWarnings("unchecked")
-            final T bagEntry = weakThreadLocals ? ((WeakReference<T>) entry).get() : (T) entry;
-            if (bagEntry != null && bagEntry.compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
-               return bagEntry;
-            }
+      final List<Object> list = threadList.get();
+      for (int i = list.size() - 1; i >= 0; i--) {
+         final Object entry = list.remove(i);
+         @SuppressWarnings("unchecked")
+         final T bagEntry = weakThreadLocals ? ((WeakReference<T>) entry).get() : (T) entry;
+         if (bagEntry != null && bagEntry.compareAndSet(STATE_NOT_IN_USE, STATE_IN_USE)) {
+            return bagEntry;
          }
       }
 
@@ -149,7 +147,7 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
          }
 
          listener.addBagItem(waiting);
-         
+
          timeout = timeUnit.toNanos(timeout);
          do {
             final long start = currentTime();
@@ -181,7 +179,7 @@ public class ConcurrentBag<T extends IConcurrentBagEntry> implements AutoCloseab
    {
       bagEntry.setState(STATE_NOT_IN_USE);
 
-      while (waiters.get() > 0) {
+      while (waiters.get() > 0 && bagEntry.getState() == STATE_NOT_IN_USE) {
          if (handoffQueue.offer(bagEntry)) {
             return;
          }