MPL reads (emphasis mine):
1.7. “Larger Work”
means a work that combines Covered Software with other material, in a separate file or files, that is not Covered Software.
3.3. Distribution of a Larger Work
You may create and distribute a Larger Work under terms of Your choice, provided that You also comply with the requirements of this License for the Covered Software. <...>
Does this mean that if
- my project contains more then 1 file,
- I accept contributions only to 1 file at a time,
- I require licensing contributions under MPL
then I can freely relicense my project with all contributions as my project would always be a larger work?
Even more, if I just add an icon to whatever project, it would cover both points 1 & 3 as it would be more then 1 file & hardly anyone would contribute to an icon.