Paths of empty pofiles must not start with a slash.

When the UI creates a new pofile (e.g. a new language is translated for the first time), it sets the the name to be <potemplate-directory>/<translationdomain>-<languagecode>.po. If the the potemplate directory is empty because the potemplate was uploaded without a template, the / is still left in. Thus the pofile path begins with a /.

This causes the file not be included in a directory named like the translationdomain when translations are exported into a tarball.

The leading / must be surpressed when creating the filename.

Source hint: POTemplate._composePOFilePath()