scc version is overwritten when called from a Git repository

Noticed by @ximenesuk, if `scc version` gets called from a Git repository, it used the `git describe` from this local repository, leading to inaccurate version

```
sebastien@sbesson:openmicroscopy (4335_clitest_script) $ ~/virtualenv/bin/scc version
v.5.0.0-beta2-51-g80819
```

More dramatically, it overwrites the `RELEASE-VERSION` file stored in scc:
```
sebastien@sbesson:~ $ ~/virtualenv/bin/scc version
v.5.0.0-beta2-51-g80819
```

This bug should be fixed in the `Version` command with a corresponding integration integration test.