Merge branch 'master' into 4.x

# Conflicts:
#	CHANGELOG.md
#	Examples/SDWebImage Demo/MasterViewController.m
#	SDWebImage.podspec
#	SDWebImage/SDWebImageDownloader.m
#	SDWebImage/SDWebImageDownloaderOperation.m
#	WebImage/Info.plist

@@ -60,6 +60,11 @@
 - Fix multiple requests for same image and then canceling one #883 + 8a78586
 - Fixed #1444 and the master build thanks to [@kenmaz](https://github.com/kenmaz/SDWebImage/commit/5034c334be50765dfe4e97c48bcb74ef64175188)
 
+## [3.8.2 Patch release for 3.8.0 on Sep 5th, 2016](https://github.com/rs/SDWebImage/releases/tag/3.8.2)
+
+#### Fixes:
+
+- Fixed #1608 #1623 #1644 Crash in `[NSURLCache cachedResponseForRequest:]` -  the fix is actually avoiding to access `NSURLCache` which appears to generate a race condition. We only call it if necesarry (`SDWebImageRefreshCached` is used and the image cannot be cached by the system when it's too big or behind authentication)
 
 ## [3.8.1 Patch release for 3.8.0 on Jun 7th, 2016](https://github.com/rs/SDWebImage/releases/tag/3.8.1)
 

@@ -70,6 +70,7 @@
         _executionOrder = SDWebImageDownloaderFIFOExecutionOrder;
         _downloadQueue = [NSOperationQueue new];
         _downloadQueue.maxConcurrentOperationCount = 6;
+        _downloadQueue.name = @"com.hackemist.SDWebImageDownloader";
         _URLOperations = [NSMutableDictionary new];
 #ifdef SD_WEBP
         _HTTPHeaders = [@{@"Accept": @"image/webp,image/*;q=0.8"} mutableCopy];

@@ -67,7 +67,7 @@ typedef NSMutableDictionary<NSString *, id> SDCallbacksDictionary;
                               inSession:(nullable NSURLSession *)session
                                 options:(SDWebImageDownloaderOptions)options {
     if ((self = [super init])) {
-        _request = request;
+        _request = [request copy];
         _shouldDecompressImages = YES;
         _options = options;
         _callbackBlocks = [NSMutableArray new];
@@ -438,12 +438,14 @@ didReceiveResponse:(NSURLResponse *)response
             completionBlock(nil, nil, error, YES);
         }
     } else {
-        if (![[NSURLCache sharedURLCache] cachedResponseForRequest:_request]) {
-            responseFromCached = NO;
-        }
-        
         if (completionBlocks.count > 0) {
-            if (self.options & SDWebImageDownloaderIgnoreCachedResponse && responseFromCached) {
+            /**
+             *  See #1608 and #1623 - apparently, there is a race condition on `NSURLCache` that causes a crash
+             *  Limited the calls to `cachedResponseForRequest:` only for cases where we should ignore the cached response
+             *    and images for which responseFromCached is YES (only the ones that cannot be cached).
+             *  Note: responseFromCached is set to NO inside `willCacheResponse:`. This method doesn't get called for large images or images behind authentication
+             */
+            if (self.options & SDWebImageDownloaderIgnoreCachedResponse && responseFromCached && [[NSURLCache sharedURLCache] cachedResponseForRequest:self.request]) {
                 for (SDWebImageDownloaderCompletedBlock completionBlock in completionBlocks) {
                     completionBlock(nil, nil, nil, YES);
                 }