Keep sindex block when initiating post construction. Could help with #2087.
Merge branch 'daniel_2073' into daniel_2087
Merge branch 'next' into daniel_2087
Just added a TODO
abandon_page() vs mark_abandon_page()
Removed a wrong assertion. Fixes #2079.
Merge branch 'next' into daniel_2087
Assign new UUIDs to backfilled sindexes. Also updated a comment.
Merge branch 'next' into sam_daniel_2108
Made catch_up_deferred_load assert page is unevictable, rather than evicted...
Fix backtraces containing r.row in JavaScript

Closes #2096
Review 1331 by @neumino
Detach first/last child moved in internal_node::level.
Merge branch 'next' into daniel_2087
Merge branch 'daniel_2073_2' into next
Merge branch 'next' into daniel_2071

Conflicts:
	src/buffer_cache/alt/page_cache.cc
Process backfills one key-value at a time, and release locks earlier when receiving backfills.