When merging a GitHub PR, the commit message is empty

[brianjmurrell]

Issue Type: Bug

When using VS Code to merge a PR, using the squash method, unlike GitHub itself, VS Code does not populate the commit message box with the commit message(s) in the PR.

VS Code version: Code 1.45.0 (d69a79b, 2020-05-07T16:10:24.511Z)
OS version: Linux x64 5.6.8-200.fc31.x86_64

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-7820HQ CPU @ 2.90GHz (8 x 3382)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on oop_rasterization: disabled_off protected_video_decode: unavailable_off rasterization: disabled_software skia_renderer: disabled_off_ok video_decode: unavailable_off viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	4, 3, 2
Memory (System)	31.28GB (5.68GB free)
Process Argv	--no-sandbox --unity-launch
Screen Reader	no
VM	0%
DESKTOP_SESSION	gnome-xorg
XDG_CURRENT_DESKTOP	GNOME
XDG_SESSION_DESKTOP	gnome-xorg
XDG_SESSION_TYPE	x11

Extensions (21)

Extension	Author (truncated)	Version
atlascode	atl	2.6.0
gitlens	eam	10.2.1
vscode-pull-request-github	Git	0.16.0
jenkins-pipeline-linter-connector	jan	1.2.0
vscode-github	Kni	0.30.3
rpm-spec	Lau	0.2.3
autoconf	mae	0.1.0
vscode-docker	ms-	1.2.0
python	ms-	2020.5.78807
remote-containers	ms-	0.117.1
remote-ssh	ms-	0.51.0
remote-ssh-edit	ms-	0.51.0
remote-ssh-explorer	ms-	0.51.0
remote-wsl	ms-	0.44.2
vscode-remote-extensionpack	ms-	0.20.0
cpptools	ms-	0.28.0
vscode-yaml	red	0.8.0
jenkins-jack	tab	1.0.1
shellcheck	tim	0.9.0
code-navigation	vik	0.2.0
vim	vsc	1.14.2

[IllusionMH]

/duplicate of microsoft/vscode-pull-request-github#1444