Update Data dialog did not show progress (Regression)

[mdk]

What steps will reproduce the problem?

1. Download some (larger) areas
2. Use "Update data" (CTRL-U)

What is the expected result?

The dialog

The progress of a single download is shown (kB in the first line).
The progress of the downloads is shown (second line)

What happens instead?

Only the size of the first download is shown. Afterwords the dialog is not longer updated (size, counter and progressbar will not be changed until end). Only the map in the background changes and show the bounding box of the actual downloaded data.
This works fine some time ago, but I have no clue which version works :-(

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

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-02-28 14:07:49 +0100 (Sun, 28 Feb 2016)
Build-Date:2016-02-28 20:07:32
Revision:9900
Relative:URL: ^/trunk

Identification: JOSM/1.5 (9900 en) Linux Ubuntu 15.10
Memory Usage: 435 MB / 876 MB (87 MB allocated, but free)
Java version: 1.8.0_66-internal-b17, Oracle Corporation, OpenJDK Server VM
VM arguments: [-Djosm.restart=true, -Djosm.home=/home/michael/.josm-latest, -Djava.net.useSystemProxies=true]
Dataset consistency test: No problems found

Plugins:
- ColumbusCSV (31772)
- FastDraw (31895)
- HouseNumberTaggingTool (31772)
- Mapillary (32040)
- OpeningHoursEditor (31772)
- RoadSigns (31895)
- SimplifyArea (31895)
- apache-commons (31895)
- apache-http (31895)
- buildings_tools (31895)
- contourmerge (1014)
- imagery-xml-bounds (31772)
- imagery_offset_db (32046)
- pbf (31772)
- poly (31772)
- public_transport (31895)
- reltoolbox (31895)
- reverter (32005)
- terracer (31895)
- turnrestrictions (31895)
- utilsplugin2 (32018)

[Don-vip]

Ticket #12621 has been marked as a duplicate of this ticket.

[Don-vip]

Milestone renamed

[Don-vip]

r9524 works, r9535 doesn't

[Don-vip]

Looks like a regression of r9529

[Don-vip]

@simon: do you know how to fix this?

[Don-vip]

Ticket #12784 has been marked as a duplicate of this ticket.

[bastiK]

In 10160/josm:

partial revert of [9529] (fixes #12583)

possibly breaking tests

[bastiK]

org.openstreetmap.josm.tools.HttpClientTest.testPost and org.openstreetmap.josm.tools.HttpClientTest.testPostZero are failing (as anticipated).

The question was to have a bug in the program (r9529 - r10159) or in the tests (before r9529 and after r10159). Fixing both at the same time is more difficult and is preferably done by someone who already knows the code (Simon ;-) ).

[Don-vip]

these tests are the only ones failing. Simon, can you please look into it?

[Don-vip]

In 10302/josm:

fix #12583 - fix unit tests by adding a new mode to HttpClient. Don't know if it's the best way to do it...