Use version 1.19.1

I believe we are affected by this bug:
golangci/golangci-lint#840.  1.19.1 is
reportedly not affected.

Author: jcharum

.travis.yml

@@ -7,7 +7,7 @@ os:
 dist: trusty
 sudo: false
 install:
-  - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.22.2
+  - curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.19.1
 script:
   - env GO111MODULE=on golangci-lint --timeout 5m run --new-from-rev "$TRAVIS_BRANCH" -v ./...
   - env GO111MODULE=on go test -v -short ./...