import-rsnapshot: exit with 1, not -1
import-rsnapshot: exit with 1, not -1

Using a negative exit code is a bashism and since we use /bin/sh to
interpret the script, we should avoid it.

This was reported by Raphael Geissert in a Debian bug report:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=772222

Signed-off-by: Gabriel Filion <143a18b53deb6612d517b2e11f8086b561f1df57@lelutin.ca>
[1dc5917c2adeeba13d1ef33dbb40691a1b67cc65@defaultvalue.org: adjust commit message]
Reviewed-by: Rob Browning <1dc5917c2adeeba13d1ef33dbb40691a1b67cc65@defaultvalue.org>
Tested-by: Rob Browning <1dc5917c2adeeba13d1ef33dbb40691a1b67cc65@defaultvalue.org>

gevaerts/bup,ToxicFrog/bup,ToxicFrog/bup,tjanez/bup,jbaber/bup,gevaerts/bup,pombredanne/bup,mhoeher/bup,jbaber/bup,jbaber/bup,pombredanne/bup,mhoeher/bup,tjanez/bup,mhoeher/bup,gevaerts/bup,ToxicFrog/bup,jbaber/bup,ToxicFrog/bup,pombredanne/bup,mhoeher/bup,mhoeher/bup,gevaerts/bup,tjanez/bup,tjanez/bup,jbaber/bup,ToxicFrog/bup,tjanez/bup,jbaber/bup,tjanez/bup,pombredanne/bup,pombredanne/bup,pombredanne/bup,gevaerts/bup,mhoeher/bup