OPAC 7.x-2.1

! [7.x-2.1] R1547: Fix OPAC ASIN plugin for ISBN-13
 ! [7.x-2.0] Merge remote branch 'origin/ft/R1425' into 7.x-2.x
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+  [ac5aae9] R1547: Fix OPAC ASIN plugin for ISBN-13
+  [e0488e4] R1484 [Follow-up]: Adds a drush opac-auth-purge command to purge authorities.
+  [8590447] R1484: Adds a drush opac-auth-purge command to purge authorities.
-- [7a4a03d] Merge remote branch 'origin/ft/R1425' into 7.x-2.x