regenerate expected PNG result with recent ImageMagick.
see 182eb94af4 in slapos repository.
fixed various issues with testnode and make it even more robust

Here the list of changes:
- close all timers when quitting, this makes stopping an erp5tetsnode
  much faster
- remove hack on slapos/testnode after fix of slapos.cookbook
- remove old tmp files left by buildout (buildout has te bo fixed too)
- remove logging handlers where the are not needed any more
- fixed the kill command, it was not able to kill properly childs
release erp5.util 0.4.25
make sure to not make erp5testnode failing if temp folder was already removed
move bt to right path, I missed it while reviewing this code
fixed undefined variable
Merge remote-tracking branch 'origin/erp5-component'
we should not reraise this OSError
release epr5.util 0.4.26
testnode was still sometimes logging at several files at a time
release erp5.util 0.4.27
Fix commit order of CMFActivity SQL connection on nodes with several zserver threads

When a ZODB connection is closed, it usually returns to a ZODB pool and may be
reused by another thread. If the SQL connection was open and is still in ZODB
cache, the _v_database_connection attribute is still there:
ActivityConnection.connect() is not called and a new instance of ZMySQLDA.db.DB
is created for the new thread without initializing its sort key.
Use already existing system preference and created accessor rather than hard coded value which was different from
default for the system preference
This can lead to different cache ids generated for same content by different
parts of the code -> duplication of same data in cache backend.
add expected failure to be fixed after
remove unused import
Fix type CMF Activity SQL connection on ERP5 Site creation

... instead of relying on automatic migration.

This fixes TestCMFActivity.test_connection_sortkey on Zope 2.13
Do not sort by default.

This hurts performances a lot.
make erp5.util.testnode able to resist to problems with slapos proxy
release erp5.util 0.4.28
make erp5.util.testnode able to resist to problems with slapos proxy