This is supposed to inhibit this warning:
```
Warning: Eager macro-expansion skipped due to cycle:
… => (load "db-utils.el") => (macroexpand-all (defalias 'db/sync-magit-repos-from-projectile …)) => (macroexpand (eval-when-compile …)) => (load "db-utils.el")
```
It should make calling this function also more robust.
Also updated the implementation to be more “dash-y”.