id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
2245	Speed up merge operation for large datasets (> 50k)	balrog-kun	dmuecke	"Merging two layers where there have been nodes in the exact same places results in broken dataset.  It seems to me, but I'm not sure, that the ""action"" tag isn't updated and always takes the value from the first layer of the two.

So for example if you work with two layers and there's a way that is in both layers, if you delete the way from the first layer, so as to avoid breakage, then after the merge the nodes of the way will all be deleted (and the way itself, not necesarily, resulting in an undeleted way between deleted nodes, which looks unusually in JOSM).  Very dangerous for big merges :-(

(Same if the nodes on the first layer have not been modified, and the nodes on the second layer had a tag added... the results will have the new tags, but will be marked unmodified)"	enhancement	closed	major		Core	latest	fixed	merge	Gubaer