Bug#908439: gtk+3.0: FTBFS with gdk-pixbuf 2.38: /Default Values/GdkPixbuf: g_bytes_new: assertion 'data != NULL || size == 0' failed

[Simon McVittie]

Source: gtk+3.0
Version: 3.24.0-1
Severity: serious
Justification: fails to build from source

While trying to address #908120 by reverting upstream commit 49b17e6c
"imwayland: clear preedit on focus out", I hit this unrelated test
failure (sorry, no debug symbols yet):

% debian/build/deb/libtool --mode=execute gdb debian/build/deb/testsuite/gtk/defaultvalue
...
(gdb) run
...
/Default Values/GdkPixbufError: OK
/Default Values/GdkPixbufFormat: OK
/Default Values/GdkPixbuf:
(/srv/tmp/smcv/build-area/gtk+3.0-3.24.0/debian/build/deb/testsuite/gtk/.libs/defaultvalue:8467): GLib-CRITICAL **: 00:19:27.089: g_bytes_new: assertion 'data != NULL || size == 0' failed

Thread 1 "defaultvalue" received signal SIGTRAP, Trace/breakpoint trap.
0x00007ffff61779f5 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
(gdb) bt
#0  0x00007ffff61779f5 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007ffff6178d0d in g_logv () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007ffff6178edf in g_log () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007ffff614ad68 in g_bytes_new () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007ffff6ce4450 in  () at /usr/lib/x86_64-linux-gnu/libgdk_pixbuf-2.0.so.0
#5  0x00007ffff625c8b8 in g_object_get_property () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
#6  0x0000555555558838 in test_type (data=<optimized out>) at ../../../../../testsuite/gtk/defaultvalue.c:373
#7  0x00007ffff6198e7a in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#8  0x00007ffff6198d34 in  () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#9  0x00007ffff6199132 in g_test_run_suite () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#10 0x00007ffff6199151 in g_test_run () at /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#11 0x000055555555779b in main (argc=<optimized out>, argv=<optimized out>)
    at ../../../../../testsuite/gtk/defaultvalue.c:495

Downgrading libgdk-pixbuf2.0-dev and closely related packages from
2.38.0+dfsg-4 to 2.36.12-2 resolves this. This might be either a
gdk-pixbuf or gtk+3.0 bug, I'm not sure yet.

Regards,
    smcv