dgraph live import sometimes fails with exit code 0

[cajus]

• What version of Dgraph are you using?
  1.0.6

• Steps to reproduce the issue (command/config used to run Dgraph).
  I've a kubernetes job set up for deploying a basic data structure into Dgraph. When the import fails (i.e. there's a typo in the initial RDF file), the job does not fail, because the exit code of dgraph live -r <> -s <> -d <> -z <> is zero.

• Expected behaviour and actual result.
  If a problem occurs during import, an exitcode != 0 should be emitted to allow callers to be sure that everything worked as expected.

Looks like

dgraph/dgraph/cmd/live/run.go

Line 352 in 3b5bc66

return

is one reason, because it doesn't trigger an error. It just returns to make the defer calls work. I thought about making a PR for that, but I'm not sure which of the three strategies for exiting is preferred. Sometimes there's just a direct os.Exit(), sometimes an indirect using log.Fatal() and sometimes another indirect using x.Checkf() which also results in a log.Fatal().