version_file's content not getting appended to the deb package's name

The version_file attribute of pkg_deb is not working correctly. The name of the debian package that bazel generates should be in the form of name_version_arch.deb which is true when you have a pkg_deb with "version". But for some reason, you end up with name__arch.deb when you have the "version_file" attribute. The .changes file does contain the version in the text file, but the name does not end up with it

On a bazel build with pkg_deb that has version:
```
builder@container:~/mybazel/bazel-bin$ ls
mydeb.deb mydeb_1.1.1_amd64.changes mydeb_1.1.1_amd64.deb mytar.manifest mytar.tar.gz src
```

On a bazel build with pkg_deb that has version_file:
```
builder@container:~/mybazel/bazel-bin$ ls
mydeb.deb mydeb__amd64.changes mydeb__amd64.deb mytar.manifest mytar.tar.gz
builder@container:~/mybazel/bazel-bin$ cat mydeb__amd64.changes
Format: 1.8
Date: Thu Jan 1 00:00:00 1970
Source: mydeb
Binary: mydeb
Architecture: amd64
Version: 1.1.1
```