Running test/presubmit-tests.sh updates go.mod and go.sum

[nak3]

Currently test/presubmit-tests.sh updates go.mod and go.sum.
Here is my env info and the step to reproduce:

0. go version

$ go version
go version go1.12.5 linux/amd64

$ git rev-parse HEAD
b6a8fa9213e40c1059d39928ca09a016dffc2eec

1. Run test/presubmit-tests.sh

$ bash test/presubmit-tests.sh 

Actual result

• go.mod and go.sum are updated. Please refer to Update go.mod and go.sum by test/presubmit-tests.sh #162 for the diff

$ git status
On branch master
Your branch is up to date with 'origin/master'.

Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)

	modified:   go.mod
	modified:   go.sum

[maximilien]

I am still puzzled at this too... and for me, often, there is a junit-report entry that is added. No idea where it comes from. Solving this is 🍺 worthy at this point, when I see you in person :)