Remove overriden attachmentNamed: from CBLUnsavedRevision

- Per code review, removed the overriden attachmentNamed: from the CBLUnsavedRevision class.
- The new added CBLAttachments get from the attachmentNamed: of the CBLUnsavedRevision will not have revision object set. Updated the unit test accordingly.

Source/API/CBLRevision.m

@@ -371,24 +371,10 @@ - (void) _addAttachment: (CBLAttachment*)attachment named: (NSString*)name {
     // NOTE: Not setting the revision to the attachment object (attachment.revision = self) as
     // [1] The UnsavedRevision object is not used during save operation
     // [2] Setting the UnsavedRevision object here will cause the circular reference memory leak.
-    // The revision object will be set in the overridden attachmentName: method.
 }
 
 - (void) removeAttachmentNamed: (NSString*)name {
     [self _addAttachment: nil named: name];
 }
 
-- (CBLAttachment*) attachmentNamed: (NSString*)name {
-    CBLAttachment* base = self.attachmentMetadata[name];
-    if (base) {
-        CBLAttachment* attachment = [[CBLAttachment alloc] _initWithContentType: base.contentType
-                                                                           body: base.body];
-        attachment.name = name;
-        attachment.revision = self;
-        return attachment;
-    }
-    return nil;
-}
-
-
 @end

Unit-Tests/Database_Tests.m

@@ -733,7 +733,8 @@ - (void) test18_Attachments {
     AssertEq(rev2.attachments.count, (NSUInteger)1);
     AssertEqual(rev2.attachmentNames, [NSArray arrayWithObject: @"index.html"]);
     CBLAttachment* attach = [rev2 attachmentNamed:@"index.html"];
-    AssertEq(attach.document, doc);
+    AssertNil(attach.revision); // No revision set
+    AssertNil(attach.document); // No revision set
     AssertEqual(attach.name, @"index.html");
     AssertEqual(attach.contentType, @"text/plain; charset=utf-8");
     AssertEqual(attach.content, body);