userpage: fix redirect on contact method change

root userpage paths ("") would mess up the redirect, wrapper function
returns "/" if thats the case. For #455.

api-userpage.go

@@ -199,7 +199,7 @@ func (app *appContext) confirmMyAction(gc *gin.Context, key string) {
 
 	// Perform an Action
 	if target == NoOp {
-		gc.Redirect(http.StatusSeeOther, PAGES.MyAccount)
+		gc.Redirect(http.StatusSeeOther, MustGetNonEmptyURL(PAGES.MyAccount))
 		return
 	} else if target == UserEmailChange {
 		app.modifyEmail(id, claims["email"].(string))
@@ -214,7 +214,7 @@ func (app *appContext) confirmMyAction(gc *gin.Context, key string) {
 		}, gc, true)
 
 		app.info.Printf(lm.UserEmailAdjusted, gc.GetString("jfId"))
-		gc.Redirect(http.StatusSeeOther, PAGES.MyAccount)
+		gc.Redirect(http.StatusSeeOther, MustGetNonEmptyURL(PAGES.MyAccount))
 		return
 	}
 }

config.go

@@ -66,6 +66,13 @@ func FixFullURL(v string) string {
 	return v
 }
 
+func MustGetNonEmptyURL(path string) string {
+	if !strings.HasPrefix(path, "/") {
+		return "/" + path
+	}
+	return path
+}
+
 func FormatSubpath(path string, removeSingleSlash bool) string {
 	if path == "/" {
 		if removeSingleSlash {