For some reason unitnostuckinfactory.lua does not help in the case of an attack move order.

This annoyed me enough I wrote a local widget. If a mobile builder is given an attack move order, this will insert a move order before. Here is the meat of it:
function widget:UnitFromFactory(unitID, unitDefID, unitTeam, factID, factDefID, userOrders)
---Order unit to move away from factory's build yard---
if ( UnitDefs[unitDefID].isMobileBuilder ) then
local cmdID, , , cmdX, cmdY, cmdZ = Spring.GetUnitCurrentCommand(factID)
-- Fight command is cmdID 16
if ( cmdID == 16 ) then
local dx,_,dz = Spring.GetUnitDirection(unitID)
local x,y,z = Spring.GetUnitPosition(unitID)
dx = dx*100 --Note: don't need trigonometry here because factory direction is either {0+-,1+-} or {1+-,0+-} (1 or 0), so multiply both with 100 elmo is enough
dz = dz*100
Spring.GiveOrderArrayToUnitArray( {unitID},{
{CMD.INSERT, {0, CMD_RAW_MOVE, CMD.OPT_INTERNAL, x+dx, y, z+dz}, CMD.OPT_ALT},
{CMD.INSERT, {1, cmdID, CMD.OPT_INTERNAL, cmdX, cmdY, cmdZ}, CMD.OPT_ALT},
})--insert move command before current fight command
end
end
end