Wrongly merging some ways

[naoliv]

With the attached file, select name=1 | waterway and then run "merge overlap" on them. Note how two ways were created: one having only name=1 and another one that is right.
It shouldn't create this duplicated way with only name=1

Sometimes (difficult to reproduce) I also see a different behavior: it properly creates only one way but without having the waterway=river tag.

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2014-10-29 02:33:50
Last Changed Author: stoecker
Revision: 7666
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2014-10-28 21:48:28 +0100 (Tue, 28 Oct 2014)
Last Changed Rev: 7666

Identification: JOSM/1.5 (7666 pt_BR) Linux Debian GNU/Linux testing (jessie)
Memory Usage: 247 MB / 8158 MB (138 MB allocated, but free)
Java version: 1.7.0_65, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u65-2.5.2-4
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

Plugins:
- Create_grid_of_ways (30762)
- OpeningHoursEditor (30737)
- PicLayer (30762)
- SimplifyArea (30695)
- buildings_tools (30762)
- contourmerge (1012)
- download_along (30762)
- editgpx (30737)
- geotools (30762)
- importvec (30762)
- jts (30762)
- log4j (30762)
- measurement (30737)
- merge-overlap (30766)
- notes (v0.9.4)
- opendata (30762)
- pbf (30762)
- pdfimport (30737)
- poly (30738)
- reverter (30737)
- scripting (30700)
- todo (29154)
- turnrestrictions (30762)
- undelete (30762)
- utilsplugin2 (30762)