It was mostly correct, except for the case where a user sets an
empty string as the export filename. What was happening is:
- STL exporter invocation adds ".stl" extension, so the path becomes
foo/.stl
- Code tries to replace extension with "ObjectName.stl", but
BLI_path_extension_replace sees that the filename part starts with
a dot and thinks the ".stl" part is the whole filename, not the
extension
- Resulting path thus becomes "foo/.stlObjectName.stl"
1ea014112b