travis: only run coverage against modern Go

.travis.yml

@@ -4,47 +4,52 @@ matrix:
   include:
     - go: 1.2
       install:
-      - go get golang.org/x/tools/cmd/cover
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test ./...
     - go: 1.3
       install:
-      - go get golang.org/x/tools/cmd/cover
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test ./...
     - go: 1.4
       install:
-      - go get golang.org/x/tools/cmd/cover
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test ./...
     - go: 1.5
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     - go: 1.6
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     - go: 1.7
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     - go: 1.8
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     - go: 1.9
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     # Important: you must force a string, else YAML will coerce to "1.1", which is NOT the version you want.
     - go: "1.10"
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
+      script: go test -cover ./...
     - go: tip
       install:
       - go list -f '{{range .Imports}}{{.}} {{end}}' ./... | xargs go get -v
       - go list -f '{{range .TestImports}}{{.}} {{end}}' ./... | xargs go get -v
-script:
-  - go test -cover ./...
+      script: go test -cover ./...