How do you verify that all the changes committed in a branch are merged back to the main branch?

[yang . wayne]

Hi,

I have a release branch created at the code freeze stage of
development.   Developers have committed all the bug fixes in the
release branch and they are responsible for merging their changes back
to main branch.  I am wondering whether there's a way to verify that
all these changes exist in main branch?

I was trying to do something like:

cvs -n update -j <release_branch_name>

in the working copy of main branch to see if there are still merges
occurring.

Thanks,