2.0.11/2.1.5 PRs & issues to backport

[rjbou]

Todo

• Expand variable interpolations in build-env #5352
• Fix crash for updates to environment with empty strings #5350
• opamClient: pass dl_cache from initConfig to config #5315
• git, hg: Use full revision #5342
• Fix opam installing packages without checking their checksum when the local cache is corrupted in some cases #5538

[hannesm]

could both of these PRs being packported? As usual, it is debatable whether these are bugfixes or features, but honestly they're both low-profile and make the behaviour of opam much more in line of user expectations (i.e. without 5315 I can't use archive-mirrors with "opam-monorepo")

• Make archive-mirrors modifiable via opam config #5321
• opamClient: pass dl_cache from initConfig to config #5315
• git, hg: Use full revision #5342

EDIT: sorry, I confused 5321 with 5315, the latter is what I'd appreciate to have in a 2.1.5 release.

[dra27]

@hannesm - no problem, both added to the list

[rjbou]

released!