ADB cleans overzealously under memory pressure

This was found in v9.19, but it applies to v9.18 and v9.16.

When the ADB is overmem, it can clean fetches that are fresh (with running fetches, etc...), see check_stale_name().

The fix for v9.19 will be different than fix for v9.18 and v9.16, but the principle is the same.

NOTE: This is an intrusive change, so v9.16 has been excluded from releases to fix.

Edited Jan 03, 2023 by Ondřej Surý

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information