Fix pathPrefix bug from PR-4025

web/web.go

@@ -666,7 +666,13 @@ func tmplFuncs(consolesPath string, opts *Options) template_text.FuncMap {
 			return time.Since(t) / time.Millisecond * time.Millisecond
 		},
 		"consolesPath": func() string { return consolesPath },
-		"pathPrefix":   func() string { return opts.RoutePrefix },
+		"pathPrefix":   func() string { 
+			if opts.RoutePrefix == "/" {
+				return ""
+			} else {
+				return opts.RoutePrefix
+			}
+		},
 		"buildVersion": func() string { return opts.Version.Revision },
 		"stripLabels": func(lset map[string]string, labels ...string) map[string]string {
 			for _, ln := range labels {