If the system only contains one library, the system preference DefaultToLoggedInLibraryCircRules is not followed. Instead, Koha will always take one to the rules for all libraries. This behavior is not documented on the syspref itself or in the manual. The related sysprefs DefaultToLoggedInLibraryNoticesSlips and DefaultToLoggedInLibraryOverdueTriggers do not behave this way. In a singl-library system, they both continue to apply as stated. This forced and undocumented behavior increases confusion. We should follow the choice on the system preference even if there is only one library.
To expand a little on why this is an issue, here's what I see frequently: - a single-library system creates all of their rules on the All Libraries page - someone clones those rules to the branch-specific page (either accidentally or in confusion) - time passes, everyone forgets the branch-specific rules are there - someone edits the All Libraries rules to reflect a change in policy - loan behavior doesn't change, because Koha is following the branch-specific rules If we force Koha to always load the All Libraries rules first for a single-library system, we are telling Koha that the first rules it shows us should always be the last rules it enforces. We're explicitly forcing the system to take the more important rules and hide them behind some clicks.