retain the error when appending the stderr output

[dvulpe]

This PR retains the Go error in sync.go:603 which should help debugging why flux fails synchronising in #3217

[stefanprodan]

LGTM

Thanks @dvulpe

[acondrat]

We seem to have the same problem and no clue to what is causing it. Any chance to see this merged/released?
Thanks!

[stefanprodan]

/rebase

[squaremo]

Isn't the err from err := cmd.Run() just going to be command exited with 1?

[dvulpe]

For the vast majority of failures you’re right. The go docs mention “other error types may be returned for other situations” as well and we need as much information as possible to understand what’s causing the flakiness.

[dvulpe]

Apologies for chasing, but we’re still seeing this flakiness in a number of fluxes and we’d like to know if there is any chance for this PR to be accepted.

[squaremo]

/rebase

[squaremo]

I beg your pardon, @dvulpe, this got crowded out by a flurry of other things going on leading up to KubeCon. I'll merge it ASAP and put it in the next release.

[dvulpe]

No worries, @squaremo - I understand how busy things can get.
I just wanted to be sure there wasn't anything else required for it to be accepted.

Thank you for merging it 🙂