fix go list command

Author: yuin

.travis.yml

@@ -6,13 +6,13 @@ go:
   - "1.11.x"
 env:
   global:
-    GO111MODULE='off'
+    GO111MODULE=off
 
 before_install:
   - go get github.com/axw/gocov/gocov
   - go get github.com/mattn/goveralls
   - if ! go get code.google.com/p/go.tools/cmd/cover; then go get golang.org/x/tools/cmd/cover; fi
 install:
-  - go get -u -v $(go list -f '{{join .Imports "\n"}}{{"\n"}}{{join .TestImports "\n"}}' ./... | sort | uniq | grep -v gopher-lua)
+  - go get -u -v $(go list -f '{{join .Imports "\n"}}{{"\n"}}{{join .TestImports "\n"}}' ./... | sort | uniq | grep '\.' | grep -v gopher-lua)
 script:
   - $HOME/gopath/bin/goveralls -service=travis-ci