Revert hashCopyN simplification fix

Partially revert #614

api-put-object-common.go

@@ -161,7 +161,7 @@ func hashCopyN(hashAlgorithms map[string]hash.Hash, hashSums map[string][]byte,
 	for k, v := range hashAlgorithms {
 		hashSums[k] = v.Sum(nil)
 	}
-	return size, nil
+	return size, err
 }
 
 // getUploadID - fetch upload id if already present for an object name

api-put-object-multipart.go

@@ -114,7 +114,9 @@ func (c Client) putObjectMultipartStream(bucketName, objectName string, reader i
 		// Calculates hash sums while copying partSize bytes into tmpBuffer.
 		prtSize, rErr := hashCopyN(hashAlgos, hashSums, tmpBuffer, reader, partSize)
 		if rErr != nil {
-			return 0, rErr
+			if rErr != io.EOF {
+				return 0, rErr
+			}
 		}
 
 		var reader io.Reader

api-put-object.go

@@ -209,9 +209,6 @@ func (c Client) putObjectSingle(bucketName, objectName string, reader io.Reader,
 		// Initialize a new temporary buffer.
 		tmpBuffer := new(bytes.Buffer)
 		size, err = hashCopyN(hashAlgos, hashSums, tmpBuffer, reader, size)
-		if err != nil {
-			return 0, err
-		}
 		reader = bytes.NewReader(tmpBuffer.Bytes())
 		tmpBuffer.Reset()
 	} else {
@@ -232,7 +229,12 @@ func (c Client) putObjectSingle(bucketName, objectName string, reader io.Reader,
 		}
 		reader = tmpFile
 	}
-
+	// Return error if its not io.EOF.
+	if err != nil {
+		if err != io.EOF {
+			return 0, err
+		}
+	}
 	// Execute put object.
 	st, err := c.putObjectDo(bucketName, objectName, reader, hashSums["md5"], hashSums["sha256"], size, metaData)
 	if err != nil {