Fix wrong error message when touching sync file fails
Fix wrong error message when touching sync file fails

We were previously assuming that any failed exit signalled that the
GC cooldown time had been exceeded but there are a number of other
reasons the command could fail. e.g., an ssh network error or system
error.

Teino1978-Corp/https-github.com-Teino1978-Corp-backup-utils,spotify/backup-utils,github/backup-utils,github/backup-utils