Johannes Schindelin [off-list ref] writes:
The non-existent editor also aborts with a non-zero status.
Thanks; that is a good point. Perhaps we might want to say what editor we
tried to run in the error message.
quoted
An editor that can exit with non-zero status on demand could use this
codepath to abort the rebase,
Removing all lines of the edit script will abort an interactive rebase.
I guess you replied too fast without reading the message to the end ;-)