Requesting a backport of libxcb and xcb-proto 1.13 for stretch-backports please. These packages are already in buster.
Rationale: Mesa 18.2.1 seems to now require libxcb 1.13, due to changes in the vulkan code. I suspect the requested packages will be needed if newer Mesa support in stretch-backports is to continue.
for detail, but basically while the code says that libxcb 1.11 onwards is supported (commit linked in bug report), it seems that a recent commit (also linked in bug report) has forced libxcb 1.13 to be required.
Basically I'm requesting this backport in anticipation that it'll be needed to support mesa 18.2.1 or later in stretch-backports, if not now, soon.
Stuart Young (aka Cefiar)