Reconciliation, when closing a file, can now see child pages in a
WT_REF_MEM state, they're empty pages we're about to merge into the
page we're reconciling.  We haven't seen this state before because the
eviction server would have set these pages to WT_REF_LOCKED during its
review of the selected page's subtree.

Relax the constraint (the only alternative I can think of would be to
switch to doing "real" eviction, where we switch the page's state to
WT_REF_LOCKED, and that has its own problems, this is a lot simpler).
typo
typo