Update gomod and vendor

vendor/github.com/moby/buildkit/source/gitidentifier.go

@@ -0,0 +1,70 @@
+package source
+
+import (
+	"net/url"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type GitIdentifier struct {
+	Remote     string
+	Ref        string
+	Subdir     string
+	KeepGitDir bool
+}
+
+func NewGitIdentifier(remoteURL string) (*GitIdentifier, error) {
+	repo := GitIdentifier{}
+
+	if !isGitTransport(remoteURL) {
+		remoteURL = "https://" + remoteURL
+	}
+
+	var fragment string
+	if strings.HasPrefix(remoteURL, "git@") {
+		// git@.. is not an URL, so cannot be parsed as URL
+		parts := strings.SplitN(remoteURL, "#", 2)
+
+		repo.Remote = parts[0]
+		if len(parts) == 2 {
+			fragment = parts[1]
+		}
+		repo.Ref, repo.Subdir = getRefAndSubdir(fragment)
+	} else {
+		u, err := url.Parse(remoteURL)
+		if err != nil {
+			return nil, err
+		}
+
+		repo.Ref, repo.Subdir = getRefAndSubdir(u.Fragment)
+		u.Fragment = ""
+		repo.Remote = u.String()
+	}
+	if repo.Subdir != "" {
+		return nil, errors.Errorf("subdir not supported yet")
+	}
+	return &repo, nil
+}
+
+func (i *GitIdentifier) ID() string {
+	return "git"
+}
+
+// isGitTransport returns true if the provided str is a git transport by inspecting
+// the prefix of the string for known protocols used in git.
+func isGitTransport(str string) bool {
+	return strings.HasPrefix(str, "http://") || strings.HasPrefix(str, "https://") || strings.HasPrefix(str, "git://") || strings.HasPrefix(str, "git@")
+}
+
+func getRefAndSubdir(fragment string) (ref string, subdir string) {
+	refAndDir := strings.SplitN(fragment, ":", 2)
+	ref = "master"
+	if len(refAndDir[0]) != 0 {
+		ref = refAndDir[0]
+	}
+	if len(refAndDir) > 1 && len(refAndDir[1]) != 0 {
+		subdir = refAndDir[1]
+	}
+	return
+}