Make IsRetryError function

fs/error.go

@@ -58,6 +58,15 @@ func RetryError(err error) error {
 	return plainRetryError{err}
 }
 
+// IsRetryError returns true if err conforms to the Retry interface
+// and calling the Retry method returns true.
+func IsRetryError(err error) bool {
+	if r, ok := err.(Retry); ok {
+		return r.Retry()
+	}
+	return false
+}
+
 // isClosedConnError reports whether err is an error from use of a closed
 // network connection.
 //

fs/operations.go

@@ -238,7 +238,7 @@ tryAgain:
 		inErr = in.Close()
 	}
 	// Retry if err returned a retry error
-	if r, ok := err.(Retry); ok && r.Retry() && tries < maxTries {
+	if IsRetryError(err) && tries < maxTries {
 		tries++
 		Log(src, "Received error: %v - low level retry %d/%d", err, tries, maxTries)
 		if removeFailedCopy(dst) {