Unnecessary since these are DUPs, the key will always be the same

Preserve DB flags (use metapage#1) when main DB is empty.
Fail if metapage root != actual root in output file.

Howard Chu authored Jan 07, 2016 and Hallvard Furuseth committed Dec 15, 2016

Logical counterpart to GET_MULTIPLE, NEXT_MULTIPLE

Add mdb_put text to mdb_cursor_put description for people who
fail to draw logical conclusions.

* Add MDB_TXN_FINISHED, MDB_TXN_HAS_CHILD, MDB_TXN_BLOCKED.
* Clear mt_numdbs in writers, for TXN_DBI_EXIST() to catch.
  We already do in readers.

David Barbour authored Jan 12, 2015 and Hallvard Furuseth committed Oct 25, 2015

commit b660491d (mdb_txn_id())
plus c36c167c (fix prev commit)
from mdb.master.

For those people who insist on ignoring the obvious.

Missed this in 7ce29b9e

Hallvard Furuseth authored Jul 11, 2015 and Howard Chu committed Jul 28, 2015

Except we don't catch the user passing F_SUBDATA to
mdb_cursor_<put/del>, like an internal LMDB call.