Fix version string check to allow properly tagged betas

cmd/syncthing/main.go

@@ -49,15 +49,16 @@ import (
 )
 
 var (
-	Version     = "unknown-dev"
-	Codename    = "Copper Cockroach"
-	BuildStamp  = "0"
-	BuildDate   time.Time
-	BuildHost   = "unknown"
-	BuildUser   = "unknown"
-	IsRelease   bool
-	IsBeta      bool
-	LongVersion string
+	Version           = "unknown-dev"
+	Codename          = "Copper Cockroach"
+	BuildStamp        = "0"
+	BuildDate         time.Time
+	BuildHost         = "unknown"
+	BuildUser         = "unknown"
+	IsRelease         bool
+	IsBeta            bool
+	LongVersion       string
+	allowedVersionExp = regexp.MustCompile(`^v\d+\.\d+\.\d+(-[a-z0-9]+)*(\.\d+)*(\+\d+-g[0-9a-f]+)?(-dirty)?$`)
 )
 
 const (
@@ -89,9 +90,8 @@ const (
 func init() {
 	if Version != "unknown-dev" {
 		// If not a generic dev build, version string should come from git describe
-		exp := regexp.MustCompile(`^v\d+\.\d+\.\d+(-[a-z0-9]+)*(\+\d+-g[0-9a-f]+)?(-dirty)?$`)
-		if !exp.MatchString(Version) {
-			l.Fatalf("Invalid version string %q;\n\tdoes not match regexp %v", Version, exp)
+		if !allowedVersionExp.MatchString(Version) {
+			l.Fatalf("Invalid version string %q;\n\tdoes not match regexp %v", Version, allowedVersionExp)
 		}
 	}