go.mod: change imports to github.com/distribution/distribution/v3

Go 1.13 and up enforce import paths to be versioned if a project
contains a go.mod and has released v2 or up.

The current v2.x branches (and releases) do not yet have a go.mod,
and therefore are still allowed to be imported with a non-versioned
import path (go modules add a `+incompatible` annotation in that case).

However, now that this project has a `go.mod` file, incompatible
import paths will not be accepted by go modules, and attempting
to use code from this repository will fail.

This patch uses `v3` for the import-paths (not `v2`), because changing
import paths itself is a breaking change, which means that  the
next release should increment the "major" version to comply with
SemVer (as go modules dictate).

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

health/api/api.go

@@ -4,7 +4,7 @@ import (
 	"errors"
 	"net/http"
 
-	"github.com/docker/distribution/health"
+	"github.com/distribution/distribution/v3/health"
 )
 
 var (

health/api/api_test.go

@@ -5,7 +5,7 @@ import (
 	"net/http/httptest"
 	"testing"
 
-	"github.com/docker/distribution/health"
+	"github.com/distribution/distribution/v3/health"
 )
 
 // TestGETDownHandlerDoesNotChangeStatus ensures that calling the endpoint

health/checks/checks.go

@@ -10,7 +10,7 @@ import (
 	"strconv"
 	"time"
 
-	"github.com/docker/distribution/health"
+	"github.com/distribution/distribution/v3/health"
 )
 
 // FileChecker checks the existence of a file and returns an error

health/doc.go

@@ -17,14 +17,14 @@
 //
 // To install health, just import it in your application:
 //
-//  import "github.com/docker/distribution/health"
+//  import "github.com/distribution/distribution/v3/health"
 //
 // You can also (optionally) import "health/api" that will add two convenience
 // endpoints: "/debug/health/down" and "/debug/health/up". These endpoints add
 // "manual" checks that allow the service to quickly be brought in/out of
 // rotation.
 //
-//  import _ "github.com/docker/distribution/health/api"
+//  import _ "github.com/distribution/distribution/v3/health/api"
 //
 //  # curl localhost:5001/debug/health
 //  {}
@@ -105,7 +105,7 @@
 // You can also use the predefined Checkers that come included with the health
 // package. First, import the checks:
 //
-//  import "github.com/docker/distribution/health/checks
+//  import "github.com/distribution/distribution/v3/health/checks
 //
 // After that you can make use of any of the provided checks. An example of
 // using a `FileChecker` to take the application out of rotation if a certain

health/health.go

@@ -7,8 +7,8 @@ import (
 	"sync"
 	"time"
 
-	"github.com/docker/distribution/context"
-	"github.com/docker/distribution/registry/api/errcode"
+	"github.com/distribution/distribution/v3/context"
+	"github.com/distribution/distribution/v3/registry/api/errcode"
 )
 
 // A Registry is a collection of checks. Most applications will use the global