Removal of Var.memo() in 6.7.0 breaks compatibility with Finagle 6.7.1

[sirmax]

While using Finagle 6.7.1 in my project I've bumped the util-core dependency to the latest 6.7.0. The result is

Exception in thread "main" java.lang.NoSuchMethodError: com.twitter.util.Var.memo()Lcom/twitter/util/Var;
    at com.twitter.finagle.Group$class.set(Group.scala:46)
    at com.twitter.finagle.Group$$anon$2.set(Group.scala:153)
    at com.twitter.finagle.Group$$anon$3.<init>(Group.scala:63)
    at com.twitter.finagle.Group$class.collect(Group.scala:60)
    at com.twitter.finagle.Group$$anon$2.collect(Group.scala:153)
    at com.twitter.finagle.Group$class.map(Group.scala:53)
    at com.twitter.finagle.Group$$anon$2.map(Group.scala:153)
    at com.twitter.finagle.client.DefaultClient$$anonfun$19.apply(DefaultClient.scala:186)
    at com.twitter.finagle.client.DefaultClient$$anonfun$19.apply(DefaultClient.scala:164)
    at scala.Function1$$anonfun$compose$1.apply(Function1.scala:49)
    at com.twitter.finagle.factory.Refinery.<init>(Refinery.scala:20)
    at com.twitter.finagle.client.DefaultClient$$anonfun$21.apply(DefaultClient.scala:199)
    at com.twitter.finagle.client.DefaultClient$$anonfun$21.apply(DefaultClient.scala:199)
    at com.twitter.finagle.builder.ClientBuilder.buildFactory(ClientBuilder.scala:815)
    …

Formally, the removed Var.memo() was in public API, so either it should have been a major release, or, preferrably, the method should have been marked as deprecated, in case if anyone has already used it.

[mosesn]

Oops, we missed this one. I thought we removed memo before moving Var from the exp package. Good catch! Unfortunately, there isn't anything we can do at this point. I think introducing a new deprecated memo at this point will just be confusing. I'm going to close this ticket for now.