The bug described in MDL-75608 has been reintroduced: the 'Expand all fieldsets' step in Behat fails when there is a single fieldset.

It is looking for the following xpath:

//legend/div[contains(concat(' ', @class, ' '), ' ftoggler ')]//a[contains(concat(' ', @class, ' '), ' icons-collapse-expand ') and @aria-expanded = 'false']

Or to put it in CSS syntax which is easier to read,

legend > div.ftoggler a.icons-collapse-expand[aria-expanded=false]

However, the 'legend' tag is now screenreader-only (I'm told this change was in MDL-74814), and this div is not within the legend. It now looks like this:

fieldset > div > div.ftoggler a.icons-collapse-expand[aria-expanded=false]

The following would match both the old and new situations and is generally looser, which is probably safer regarding potential custom themes, with the only risk being if somebody uses 'ftoggler' somewhere inside a form (except for these fieldset expanders) it might very rarely do the wrong thing:

fieldset div.ftoggler a.icons-collapse-expand[aria-expanded=false]

//fieldset//div[contains(concat(' ', @class, ' '), ' ftoggler ')]//a[contains(concat(' ', @class, ' '), ' icons-collapse-expand ') and @aria-expanded = 'false']

I will do another fix. This time I will also incorporate the Behat test so that we can stop breaking it in future...