While working on refactoring code, David Maus has discovered some issues with the way our searchspecs.yaml file is formatted. See:
It turns out that the Horde_YAML component we have been relying on for parsing these files is not very faithful to the YAML specification, and some of the syntax we have been using is tailored for eccentricities of the Horde parser rather than the actual standard.
As of this morning, I have corrected all of our YAML files so that they comply with the standard AND can be parsed correctly by the Horde_YAML module. If you have customized your YAML files, you may want to take a look at these changes (see patches on the two tickets above) and adjust them to match so you don't get any nasty surprises the next time you upgrade.
I will continue to use Horde_YAML in VuFind 1.x for now since it is PHP 5.2-compatible. However, for VuFind 2.0, I have taken David's suggestion and switched to the Symfony/Yaml component (see VUFIND-715 in JIRA). This should prevent us from drifting away from the standard in the future, and it also seems to be a more actively developed library. As an added bonus, it has allowed me to finally remove an ugly Horde-related hack from the default searchspecs.yaml (see VUFIND-160).
Please let me know if you have questions or problems. I don't enjoy making potentially disruptive changes like this, but in this particular case, it seems better to fix this problem now than to let it go and have larger problems down the road.