Entries are missing on the cvsweb log for numerous branches. For example: http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/configure.diff?cvsroot=gcc&only_with_tag=gcc-3_4-branch&f=h&r1=1.794.2.10&r2=1.794.2.12 is present, but click on the "Return to configure" link (http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/configure?cvsroot=gcc&f=h&only_with_tag=gcc-3_4-branch#rev1.794.2.12) and you'll see that none of the associated check-ins to the gcc-3_4-branch are present in the web view of CVS log. This may be related to PR web/11335.
Confirmed.
I'm closing this bug as the subversion-pushed move to viewcvs has made the problem go away. http://gcc.gnu.org/viewcvs/branches/gcc-3_4-branch/gcc/configure?view=log