Re: (ITS#7651) LMDB: Uncontrolled database when opened from multiple processes

I'd call this two doc bugs:

Something should mention that once a page has been used, the file will never shrink below that page. (Can't quite say that the file never shrinks, since WRITEMAP and Windows will set it to exact re-configurable mapsize in some cases. If I remember correctly.)

mdb_env_copy() and mdb_env_copyfd() should document that

@node This call can trigger siginficant file size growth if run in parallel with write transactions, because it employs a read-only transaction. See long-lived transactions under Caveats.

I wonder that means these functions should have a flag parameter. For some databases, users might prefer a _write_ transaction while reading the DB, blocking writes while copying.