cvs2svn says: # The first revision on a vendor branch is always the same as # the revision from which the branch sprouts, e.g., 184.108.40.206 is # always the same as 1.1, so there's no need to further modify # 220.127.116.11 from however it is in the copy from 1.1. This is false. Example: 1) Add+commit a file normally 2) Import a file of the same name There is no guarantee that these were identical Or, more rigourously: mkdir testroot cd testroot export CVSROOT=`pwd`/testrepo cvs init cvs co -d testwc -l . cd testwc mkdir foo cvs add foo cd foo echo "Hello" > foo cvs add foo cvs ci -m. mkdir tmp cd tmp echo "Goodbye" > foo cvs import -m. foo VENDOR IMPORT1 cd .. cvs co -p -r 1.1 foo/foo cvs co -p -r 18.104.22.168 foo/foo cd ../.. cvs2svn --dump-only testrepo fgrep Goodbye cvs2svn-dump # Look! Contents of rev 22.214.171.124 are not in dumpfile! Probably, the solution is to just rip out the special-casing of the first revision on vendor branches.