This is a followup from https://phabricator.wikimedia.org/T183789
```
rafid@tools-sgebastion-07:~/pywikibot-core$ python3 pwb.py scripts/download_dump.py -filename:pagelinks.sql.gz
Downloading dump from idwiki
Symlinking file from /public/dumps/public/idwiki/20201020/idwiki-20201020-pagelinks.sql.gz
Done! File stored as ./idwiki-latest-pagelinks.sql.gz
rafid@tools-sgebastion-07:~/pywikibot-core$ python3 pwb.py scripts/download_dump.py -filename:pagelinks.sql.gz -dumpdate:20200601
Downloading dump from idwiki
Symlinking file from /public/dumps/public/idwiki/20201020/idwiki-20201020-pagelinks.sql.gz
Done! File stored as ./idwiki-20200601-pagelinks.sql.gz
```
As we can look above, when we provide the `dumpdate` parameter for the script when we're in toolforge, it makes a symlink to the `latest` version (it doesn't use the `dumpdate` parameter to do this) and save that symlink with `dumpdate` in the filename (instead of latest), which is erroneous.
It has to symlink to the right `dumpdate` file instead of the `latest` dump date.