What version of Go are you using (go version)?

go version go1.11rc1 darwin/amd64

Does this issue reproduce with the latest release?

YES

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/valbaev/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/valbaev/go"
GOPROXY=""
GORACE=""
GOROOT="/Users/valbaev/sdk/go1.11rc1"
GOTMPDIR=""
GOTOOLDIR="/Users/valbaev/sdk/go1.11rc1/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/valbaev/Projects/my/bzzz/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/fx/4r69fc5d0wg0nh49b69gkj_m0000gn/T/go-build297142414=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

1. Create project based on https://github.com/labstack/echo, for example "Hello world" from here https://echo.labstack.com/guide
2. Execute go mod init
3. Execute go get github.com/labstack/echo@6d227dfea4d2e52cb76856120b3c17f758139b4e
4. Execute go mod edit -require github.com/labstack/echo@6d227dfea4d2e52cb76856120b3c17f758139b4e
5. Execute go mod tidy

What did you expect to see?

As described in https://tip.golang.org/cmd/go/#hdr-Pseudo_versions:
Pseudo-versions never need to be typed by hand: the go command will accept the plain commit hash and translate it into a pseudo-version (or a tagged version if available) automatically. This conversion is an example of a module query.

1. After step 3, in $GOPATH/pkg/mod/github.com/labstack/ directory, I expect to see the subdirectory of echo package with pseudo-version pointed to specified commit 6d227dfea4d2e52cb76856120b3c17f758139b4e
2. After step 5 I expect to thew record pointed to echo package with commit 6d227dfea4d2e52cb76856120b3c17f758139b4e

What did you see instead?

In project's go.mod file and in $GOPATH/pkg/mod/github.com/labstack/ directory always present only echo@v3.2.2-0.20180412143600-6d227dfea4d2+incompatible version.