When using meld 1.8.1 (latest available for Fedora or in koji) "meld ." in a subversion 1.6 working directory does not trigger the "comparison to svn base" mode. The regression seems to be related to support for subversion 1.7, which adopts a different .svn layout. The problem is known upstream, and currently fixed in version 1.8.2; please just build 1.8.2 for Fedora (a self-built 1.8.2 rpm worked for me).
meld-1.8.2-1.fc19 has been submitted as an update for Fedora 19. https://admin.fedoraproject.org/updates/meld-1.8.2-1.fc19
meld-1.8.2-1.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/meld-1.8.2-1.fc18
meld-1.8.2-1.fc20 has been submitted as an update for Fedora 20. https://admin.fedoraproject.org/updates/meld-1.8.2-1.fc20
Package meld-1.8.2-1.fc20: * should fix your issue, * was pushed to the Fedora 20 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing meld-1.8.2-1.fc20' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2013-19780/meld-1.8.2-1.fc20 then log in and leave karma (feedback).
*** Bug 986671 has been marked as a duplicate of this bug. ***
meld-1.8.2-1.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.
meld-1.8.2-1.fc19 has been pushed to the Fedora 19 stable repository. If problems still persist, please make note of it in this bug report.
meld-1.8.2-1.fc20 has been pushed to the Fedora 20 stable repository. If problems still persist, please make note of it in this bug report.