Attached is a proposed NMU fixing this bug (identical to my original patch other than adding the changelog entry; the olefile issue noted above was a bug in pillow, which has now been fixed).
As the execnet issue (#840823) now also appears to have a fix, this will allow blockdiag's ~30 rdeps to stay in stretch.
diff -Nru blockdiag-1.5.3+dfsg/debian/changelog blockdiag-1.5.3+dfsg/debian/changelog --- blockdiag-1.5.3+dfsg/debian/changelog 2016-10-11 02:21:04.000000000 +0100 +++ blockdiag-1.5.3+dfsg/debian/changelog 2017-01-22 22:14:34.000000000 +0000 @@ -1,3 +1,10 @@ +blockdiag (1.5.3+dfsg-1.1) unstable; urgency=medium + + * Non-maintainer upload. + * Don't fail tests on a harmless wand warning. Closes: #848478 + + -- Rebecca N. Palmer <rebecca_pal...@zoho.com> Sun, 22 Jan 2017 22:13:59 +0000 + blockdiag (1.5.3+dfsg-1) unstable; urgency=medium * New upstream release. Closes: #801314 diff -Nru blockdiag-1.5.3+dfsg/debian/patches/848748-exception-ignored-in-Image-del.patch blockdiag-1.5.3+dfsg/debian/patches/848748-exception-ignored-in-Image-del.patch --- blockdiag-1.5.3+dfsg/debian/patches/848748-exception-ignored-in-Image-del.patch 1970-01-01 01:00:00.000000000 +0100 +++ blockdiag-1.5.3+dfsg/debian/patches/848748-exception-ignored-in-Image-del.patch 2017-01-09 22:32:13.000000000 +0000 @@ -0,0 +1,38 @@ +Description: Fix test failure with wand 0.4.1+ + +wand 0.4.1 added an Image.destroy() +(https://sources.debian.net/src/wand/0.4.4-1/wand/image.py/#L2760) that +iterates over self.sequence (the frames of an animation) to free their +memory; this throws an exception on single images (where +self.sequence=None), but as this is called from __del__, this +exception is warned about then ignored +(https://docs.python.org/3/reference/datamodel.html#object.__del__), +and hence is not an error in normal use. + +However, blockdiag tests that use capture_stderr fail on any output +containing "Traceback", including this warning message. + +This patch ignores this message to allow blockdiag to build. + +Author: Rebecca Palmer <rebecca_pal...@zoho.com> +Bug-Debian: https://bugs.debian.org/848748 +Forwarded: no + +--- blockdiag-1.5.3+dfsg.orig/src/blockdiag/tests/utils.py ++++ blockdiag-1.5.3+dfsg/src/blockdiag/tests/utils.py +@@ -64,7 +64,14 @@ def capture_stderr(func): + + func(*args, **kwargs) + +- if re.search('(ERROR|Traceback)', sys.stderr.getvalue()): ++ filtered_stderr=re.sub(r"""Exception ignored in: <bound method Resource\.__del__ of <wand\.image\.Image: \(empty\)>> ++Traceback \(most recent call last\): ++ File "/usr/lib/python3/dist-packages/wand/resource\.py", line [0-9]+, in __del__ ++ self\.destroy\(\) ++ File "/usr/lib/python3/dist-packages/wand/image\.py", line [0-9]+, in destroy ++ for i in range\(0, len\(self\.sequence\)\): ++TypeError: object of type 'NoneType' has no len\(\)""","",sys.stderr.getvalue())#this is the expected result of freeing a single image (as opposed to an animation) in wand 0.4, not a blockdiag bug - #848748 ++ if re.search('(ERROR|Traceback)', filtered_stderr): + raise AssertionError('Caught error') + finally: + if sys.stderr.getvalue(): diff -Nru blockdiag-1.5.3+dfsg/debian/patches/series blockdiag-1.5.3+dfsg/debian/patches/series --- blockdiag-1.5.3+dfsg/debian/patches/series 2016-10-11 01:32:49.000000000 +0100 +++ blockdiag-1.5.3+dfsg/debian/patches/series 2017-01-09 21:50:32.000000000 +0000 @@ -1 +1,2 @@ Fixed-remote-image-resouces.patch +848748-exception-ignored-in-Image-del.patch