优化

app/src/main/java/io/legado/app/lib/webdav/WebDav.kt

@@ -160,11 +160,13 @@ class WebDav(urlStr: String) {
         if (url != null && auth != null) {
             //防止报错
             return kotlin.runCatching {
+                if (!exists()) {
                     okHttpClient.newCallResponseBody {
                         url(url)
                         method("MKCOL", null)
                         addHeader("Authorization", Credentials.basic(auth.user, auth.pass))
                     }.close()
+                }
             }.isSuccess
         }
         return false