With Subversion 1.5 or later the merge is recorded on your local working copy in the svn:mergeinfo property. So this information is not lost.
You can see the merged revisions if you use svn log -g
The log file containing the information referenced will usually be the one named with the hostname on which Tomcat is running. On a simple server (e.g. development environment) this is localhost.<datestamp>.log
To debug lock timeout errors, set derby.locks.monitor=true and derby.locks.deadlockTrace=true in derby.properties. This will print the lock table information to the derby.log when the timeout happens. If you also set derby.language.logStatementText=true, then all the statements executed on the system will be written out to the derby.log