CVS bug?

[Damjan Zemljic]

Hi,
I created a branch on one file just to have that tag in CVS repository. 
Nothing has been commited yet to this branch. Then I've checkouted 
files with:
cvs co -R -f -r <branch_name> <module>
(from branch and missing from HEAD)

After that, I patched the files of module and wanted to commit changes 
(excpeted to commit to <branch_name>). I got "up-to-date check failed" 
and CVS server refused to commit.
I found out that after making branch explicitly on that file:
cvs tag -b <branch_name> <patched_file>
...commit succeeded.(?!)

Adding new files to "branch only" worked as expected. No, up-to-date 
complaint and new file was visible on branch only.

Is this a bug of cvs version 1.11p1 or agreed CVS behaviour. I'm pretty 
sure CVS made automaticaly branch for commited changes in previous releases.

Best regards,
Damjan