PR analysis failure for missing .lookout.yml

[carlosms]

Needs more testing, but apparently sometimes the PR analysis fails if .lookout.yml is missing.

{"app":"lookoutd","duration":183368720,"event-id":"0149ce286ddbed54c8e34bd8c7b80027614997a5","event-type":2,"head":"refs/pull/21/head","level":"debug","msg":"references [refs/pull/21/head:refs/pull/21/head] fetched for repository git://github.com/carlosms/lookout-test.git","pr-id":219656758,"pr-number":21,"provider":"github","repo":"https://github.com/carlosms/lookout-test","repository":"git://github.com/carlosms/lookout-test.git","source":"git/syncer.go:73","time":"2018-10-02T10:32:55.358396891Z"}
{"app":"lookoutd","error":"Can't get .lookout.yml in revision {git://github.com/carlosms/lookout-test.git refs/pull/21/head a20b92abad9bd6bb6b35e05eaf70e86f4f388fda}: object not found","event-id":"0149ce286ddbed54c8e34bd8c7b80027614997a5","event-type":2,"level":"error","msg":"event processing failed","pr-id":219656758,"pr-number":21,"repo":"https://github.com/carlosms/lookout-test","source":"server/server.go:98","time":"2018-10-02T10:32:55.358842832Z"}

[carlosms]

Trying a new PR (from the same branch), the analysis is performed. We get this error log in the log:

{"app":"lookoutd","event-id":"5594b1f8ed92654657e58c096cdf892f737cb7bc","event-type":2,"head":"refs/pull/22/head","level":"info","msg":"repository config is not found","pr-id":219660811,"pr-number":22,"provider":"github","repo":"https://github.com/carlosms/lookout-test","repository":"git://github.com/carlosms/lookout-test.git","source":"server/server.go:216","time":"2018-10-02T10:49:34.958600931Z"}

For the first failed PR, the error comes from

lookout/server/server.go

Line 204 in 16b5049

return nil, fmt.Errorf("Can't get .lookout.yml in revision %s: %s", rev.Head, err)

The second successful PR,

lookout/server/server.go

Line 216 in 16b5049

ctxlog.Get(ctx).Infof("repository config is not found")

[smacker]

For the last 7 days lookout is running on staging I don't see this error anymore.

[smacker]

Found it again in logs. Looks like it happens after push force.

Maybe there is a lag on gh side?
We get event but the reference isn't available yet?

I see a similar issue sometimes in drone: https://drone.srcd.host/src-d/lookout/353
it can't clone after push force from time to time.

[smacker]

Confirm about push force.

I checked logs again. This error happens very rarely. But all the errors I see were caused by push-force (I went manually to each PR and checked)