Was attempting to merge a branch in one of my projects and upon
committing the merge, I kept getting this error:

mojo-jojo david% svn commit -m "merge in the maven branch"
Sending        trunk
Sending        trunk/.classpath
Sending        trunk/.project
Adding         trunk/.settings
svn: Commit failed (details follow):
svn: Server sent unexpected return value (502 Bad Gateway) in response
to COPY request for '/svn/eddie/!svn/bc/314/branches/maven/.settings'

A quick search found several other people having the same problem.
Seems it only happens for https repositories using mod_dav_svn.
The solution is to make sure that your virtual host in apache has
explicit SSL config options, even if you are using an SSL config from a
default virtual host. For example, I added the following to my
subversion vhost, which was just copied from my default vhost:

SSLEngine on
SSLCertificateFile /etc/apache2/ssl/catnip.org.uk.crt
SSLCertificateKeyFile /etc/apache2/ssl/catnip.org.uk.key