René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Something fishy in png reading","articleBody":"We're seeing spurious test failures like:\n\n```\n======================================================================\nERROR: matplotlib.tests.test_cycles.test_marker_cycle.test\n----------------------------------------------------------------------\nTraceback (most recent call last):\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/nose/case.py\", line 197, in runTest\n    self.test(*self.arg)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py\", line 53, in failer\n    result = f(*args, **kwargs)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/decorators.py\", line 210, in do_test\n    self._tol, in_decorator=True)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python2.7/site-packages/matplotlib-1.5.0+34.g43afdd8-py2.7-linux-x86_64.egg/matplotlib/testing/compare.py\", line 314, in compare_images\n    actualImage = _png.read_png_int(actual)\nRuntimeError: Error setting jump\n```\n\nand \n\n```\n======================================================================\nERROR: matplotlib.tests.test_cycles.test_marker_cycle.test\n----------------------------------------------------------------------\nTraceback (most recent call last):\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/nose/case.py\", line 198, in runTest\n    self.test(*self.arg)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/decorators.py\", line 53, in failer\n    result = f(*args, **kwargs)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/decorators.py\", line 210, in do_test\n    self._tol, in_decorator=True)\n  File \"/home/travis/build/matplotlib/matplotlib/venv/lib/python3.4/site-packages/matplotlib-1.5.0+34.g43afdd8-py3.4-linux-x86_64.egg/matplotlib/testing/compare.py\", line 314, in compare_images\n    actualImage = _png.read_png_int(actual)\nSystemError: error return without exception set\n```\n\nWhile there were recent changes to PNG _writing_, there haven't been recent changes to PNG _reading_, so I'm not sure what's up.  But probably shouldn't let this slide...\n","author":{"url":"https://github.com/mdboom","@type":"Person","name":"mdboom"},"datePublished":"2015-11-16T23:58:05.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":8},"url":"https://github.com/5495/matplotlib/issues/5495"}