serve webdav: fix --baseurl handling after lib/http refactor

The webdav library was confused by the Path manipulation done by
lib/http when stripping the prefix.

This patch adds the prefix back before calling it.

Fixes #6650

cmd/serve/webdav/webdav.go

@@ -237,6 +237,9 @@ func (w *WebDAV) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
 		w.serveDir(rw, r, remote)
 		return
 	}
+	// Add URL Prefix back to path since webdavhandler needs to
+	// return absolute references.
+	r.URL.Path = w.opt.HTTP.BaseURL + r.URL.Path
 	w.webdavhandler.ServeHTTP(rw, r)
 }
 

cmd/serve/webdav/webdav_test.go

@@ -51,6 +51,7 @@ func TestWebDav(t *testing.T) {
 	start := func(f fs.Fs) (configmap.Simple, func()) {
 		opt := DefaultOpt
 		opt.HTTP.ListenAddr = []string{testBindAddress}
+		opt.HTTP.BaseURL = "/prefix"
 		opt.Auth.BasicUser = testUser
 		opt.Auth.BasicPass = testPass
 		opt.Template.Path = testTemplate