你应该试试:

libraryDependencies += "org.specs2" %% "specs2" % "1.7-SNAPSHOT" % "test" changing()

changed() 将指定依赖项可以改变，并且它必须在每次 update 时下载它.

changing() will specify that the dependency can change and that it ivy must download it on each update.

也许您也可以尝试使用 ivyXML 定义您的存储库.像这样:

Maybe you could also try to define your repository using ivyXML. Something like this :

ivyXML :=
  <resolvers>
        <ibiblio name="specs2 snapshot repo" changingPattern="*-SNAPSHOT" m2compatible="true" root="http://scala-tools.org/repo-snapshots"/>
  </resolvers>

希望这会有所帮助.