Fix failing pal labeling canvas test

Make sure image dpi respects mapsettings dpi in
QgsMapRendererSequentialJob.

Also apply a workaround to avoid segfault on end of test. This
workaround probably should be moved to QgsApplication::exitQgis()
but I'll do that after release in case of regressions.

.travis.yml

@@ -25,5 +25,5 @@ install:
   - cmake -DWITH_SERVER=ON -DWITH_STAGED_PLUGINS=OFF -DWITH_GRASS=OFF \
           -DSUPPRESS_QT_WARNINGS=ON -DENABLE_MODELTEST=ON -DWITH_QWTPOLAR=OFF -DWITH_APIDOC=ON ..
 
-script: xvfb-run ctest -V -E 'PyQgsPalLabelingCanvas|PyQgsPalLabelingServer|qgis_wcsprovidertest' -S ../qgis-test-travis.ctest --output-on-failure
+script: xvfb-run ctest -V -E 'PyQgsPalLabelingServer|qgis_wcsprovidertest' -S ../qgis-test-travis.ctest --output-on-failure
 

src/core/qgsmaprenderersequentialjob.cpp

@@ -29,6 +29,8 @@ QgsMapRendererSequentialJob::QgsMapRendererSequentialJob( const QgsMapSettings&
   QgsDebugMsg( "SEQUENTIAL construct" );
 
   mImage = QImage( mSettings.outputSize(), mSettings.outputImageFormat() );
+  mImage.setDotsPerMeterX( 1000 * settings.outputDpi() / 25.4 );
+  mImage.setDotsPerMeterY( 1000 * settings.outputDpi() / 25.4 );
 }
 
 QgsMapRendererSequentialJob::~QgsMapRendererSequentialJob()

tests/src/python/test_qgspallabeling_canvas.py

@@ -17,9 +17,10 @@ __copyright__ = 'Copyright 2013, The QGIS Project'
 # This will get replaced with a git SHA1 when you do a git archive
 __revision__ = '$Format:%H$'
 
+import qgis
 import sys
 import os
-from PyQt4.QtCore import qDebug
+from PyQt4.QtCore import qDebug, QThreadPool
 
 from utilities import (
     getTempfilePath,
@@ -49,6 +50,8 @@ class TestCanvasBase(TestQgsPalLabeling):
         TestQgsPalLabeling.tearDownClass()
         cls.removeMapLayer(cls.layer)
         cls.layer = None
+        #avoid crash on finish, probably related to https://bugreports.qt.io/browse/QTBUG-35760
+        QThreadPool.globalInstance().waitForDone()
 
     def setUp(self):
         """Run before each test."""