Baseline: 914db36648ef734b9b534d2a37907b9505534399
Cherry picks:
+ 7e689a55ccdcd752c102d25fe9acb257bd7d881c:
Be resilient to outdated exec paths in action cache entries
Important changes:
- The format of canonical repo names has changed to use plus (`+`)
instead of tilde (`~`). Effectively, this flips the flag
`--incompatible_use_plus_in_repo_names` to true, and the flag is
now a no-op (i.e. cannot be "unflipped").
This release contains contributions from many people at Google, as well as Fabian Meumertzheim, Jordan Mele, Laurent Le Brun, Xdng Yng.