Using Synchronizer to compare content with ftp server generates errors for files with the length of 0 bytes. It stops on every single file which size is 0 bytes and shows error dialog. Example error message "IO error at comparing file /home/user/test/a.txt with ftp://user@ftp.server.com/test/a.txt!". Its an old bug that annoys when you synchronize big structure of files.

Reproducible: Always

Steps to Reproduce:
1. Create new test folder and new empty file inside
2. Copy folder to ftp server
3. Synchronize content of folder with option "Compare by content"
Actual Results:  
Error message. Example: "IO error at comparing file /home/user/test/a.txt with ftp://user@ftp.server.com/test/a.txt!".

Expected Results:  
Synchronize directory without error messages.