Add support for upstream tag that is not <version> or v<version>

e.g. github.com/lxc/lxd with tag lxd-4.8

Fixes #139

Author: anthonyfok

make.go

@@ -107,6 +107,7 @@ type upstream struct {
 	tarPath     string   // path to the downloaded or generated orig tarball tempfile
 	compression string   // compression method, either "gz" or "xz"
 	version     string   // Debian package upstream version number, e.g. 0.0~git20180204.1d24609
+	tag         string   // Latest upstream tag, if any
 	commitIsh   string   // commit-ish corresponding to upstream version to be packaged
 	remote      string   // git remote, set to short hostname if upstream git history is included
 	firstMain   string   // import path of the first main package within repo, if any
@@ -144,16 +145,16 @@ func (u *upstream) tarballFromHoster() error {
 
 	switch repoU.Host {
 	case "github.com":
-		tarURL = fmt.Sprintf("%s/archive/v%s.tar.%s",
-			repo, u.version, u.compression)
+		tarURL = fmt.Sprintf("%s/archive/%s.tar.%s",
+			repo, u.tag, u.compression)
 	case "gitlab.com":
 		parts := strings.Split(repoU.Path, "/")
 		if len(parts) < 3 {
 			return fmt.Errorf("Incomplete repo URL: %s", u.rr.Repo)
 		}
 		project := parts[2]
-		tarURL = fmt.Sprintf("%s/-/archive/v%[3]s/%[2]s-%s.tar.%s",
-			repo, project, u.version, u.compression)
+		tarURL = fmt.Sprintf("%s/-/archive/%s/%s-%s.tar.%s",
+			repo, u.tag, project, u.tag, u.compression)
 	default:
 		return fmt.Errorf("Unsupported hoster")
 	}

version.go

@@ -9,6 +9,7 @@ import (
 	"strconv"
 	"strings"
 	"time"
+	"unicode"
 )
 
 var (
@@ -37,6 +38,7 @@ func pkgVersionFromGit(gitdir string, u *upstream, forcePrerelease bool) (string
 	if out, err := cmd.Output(); err == nil {
 		latestTag = strings.TrimSpace(string(out))
 		u.hasRelease = true
+		u.tag = latestTag
 		log.Printf("Found latest tag %q", latestTag)
 
 		if !semverRegexp.MatchString(latestTag) {
@@ -64,7 +66,9 @@ func pkgVersionFromGit(gitdir string, u *upstream, forcePrerelease bool) (string
 		}
 
 		u.commitIsh = latestTag
-		u.version = strings.TrimPrefix(latestTag, "v")
+		u.version = strings.TrimLeftFunc(latestTag, func(r rune) bool {
+			return !unicode.IsNumber(r)
+		})
 
 		if forcePrerelease {
 			log.Printf("INFO: Force packaging master (prerelease) as requested by user")