[QGIS-Developer] Merge of shapefiles to GPKG fails

[Patrick Dunford]

I have saved a shapefile to a GPKG and I want to merge some other 
shapefiles into the GPKG using the Data Management Tools -> Merge Vector 
Layers feature.

The existing GPKG is used as one of the source layers and the other 
layers are SHP. The merged layer is created as a temporary layer.

The merge proceeds as expected but when attempting to save the merged 
layer to a new GPKG it fails because the fid fields in the merged 
shapefiles have not been set to a value and contain nulls. If the values 
are copied and pasted from a shapefile to a GPKG these values are 
automatically generated as should be the case for the merge tool.

I want to use the merge tool because copying and pasting between layers 
constantly freezes. However it seems there is a problem with the merge 
tool because the values of the fid field are not being auto-generated.