ant prepare-release-no-sign fails intermittently [LUCENE-7033]

Mike reported this on the mailing list. This is fully reproducible, you just need to run it twice:

```Java
cd lucene
# succeeds
ant prepare-release-no-sign
# fails
ant prepare-release-no-sign
```

The problem is with this target that runs conditionally:

```Java









```

I attach a diff from the two runs – you can see the second one skipped this task and then cleaned the output folder, which doesn't make sense.

I don't know how to fix, but I think it's this.


---
Migrated from [LUCENE-7033](https://issues.apache.org/jira/browse/LUCENE-7033) by Dawid Weiss (@dweiss), updated Feb 20 2016
Attachments: [capture-2.png](https://apache.github.io/lucene-jira-archive/attachments/LUCENE-7033/capture-2.png)

Run `ant prepare-release-no-sign` twice from the `lucene` directory and compare the outcomes with the attached diff. Then inspect the `-unpack-lucene-tgz` target, especially its conditional execution and cleanup behavior. Done means repeated runs complete successfully without incorrectly skipping unpacking or removing the output folder.

Written by the indexing model from the issue text.