Empty field when selecting the first item in the drop down for specifying the data source for the first time

[anonymous]

What steps will reproduce the problem?

1. Do edits. Upload changes.
2. In the upload dialog box, click on the drop down for specifying the data source.
3. On your first click on the first item, the field is left empty.
4. Repeat the drop-down selection, and click the first item again to finally select it.

What is the expected result?

First item gets selected.

What happens instead?

Field is left blank

Please provide any additional information below. Attach a screenshot if possible.

Upload dialog box, initial state: ​http://imgur.com/KjHXO3Ql.png
Select first item in drop-down box: ​http://imgur.com/bdf2rSyl.png
Selecting the first item results in an empty field: ​http://imgur.com/aNLnAA3l.png
Repeat last step, and item finally gets selected: ​http://imgur.com/jE6hVS1l.png

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-11-26 14:31:59 +0100 (Sun, 26 Nov 2017)
Build-Date:2017-11-26 13:34:54
Revision:13170
Relative:URL: ^/trunk

Identification: JOSM/1.5 (13170 en) Linux Ubuntu 16.04.3 LTS
Memory Usage: 447 MB / 3500 MB (115 MB allocated, but free)
Java version: 1.8.0_151-8u151-b12-0ubuntu0.16.04.2-b12, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Java package: openjdk-8-jre:amd64-8u151-b12-0ubuntu0.16.04.2
VM arguments: [-Djosm.restart=true, -Djava.net.useSystemProxies=true]
Program arguments: [${HOME}/Documents/default.joz]
Dataset consistency test: No problems found

Plugins:
+ EasyPresets (1512175382)
+ ElevationProfile (33815)
+ FastDraw (33731)
+ ImproveOsm (126)
+ Mapillary (v1.5.9)
+ OpeningHoursEditor (33876)
+ apache-commons (33668)
+ apache-http (32699)
+ buildings_tools (33735)
+ continuosDownload (68)
+ contourmerge (1032)
+ fieldpapers (v0.4.3)
+ geojson (73)
+ imagery_offset_db (33774)
+ measurement (33760)
+ merge-overlap (33848)
+ reverter (33865)
+ scripting (30775)
+ tageditor (33806)
+ terracer (33839)
+ todo (30303)
+ turnrestrictions (33780)
+ utilsplugin2 (33742)

Map paint styles:
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip
+ https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1

Last errors/warnings:
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.net.SocketException: Socket closed
- E: java.net.SocketException: Socket closed

[GOwin]

This issue doesn't occur if you make the selection using the keyboard.

[OceanVortex]

This simple bug has annoyed me for a very long time.