Discard Changes on unstaged file will abort the current merge

[vscodebot]

Issue Type: Bug

These steps may be more specific than they need to be, but they're what I was following:

1. From a clean working directory, merge changes from another branch that produce a conflicted file.
2. Note that 'git status' reflects that you are currently in the middle of a merge.
3. Add the conflicted file to the staging area so all conflicts appear resolved.
4. Make another change to the conflicted file, so it is reflected as an unstaged change.
5. Click the "Discard Changes" button on the unstaged file to revert the change you made in step 4.

Expected behavior: I should be back where I was at the end of step 3 -- with my unstaged change removed, but still in a merging state.

Actual behavior: The unstaged change is correctly removed, but 'git status' reflects that I am no longer merging. I am unable to complete the merge without restarting it from the beginning.

VS Code version: Code 1.43.0 (78a4c91400152c0f27ba4d363eb56d2835f9903a, 2020-03-09T19:47:57.235Z)
OS version: Windows_NT x64 10.0.17763

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8850H CPU ! 2.60GHz (12 x 2592)
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: enabled rasterization: enabled skia_renderer: disabled_off_ok video_decode: enabled viz_display_compositor: enabled_on viz_hit_test_surface_layer: disabled_off_ok webgl: enabled webgl2: enabled
Load (avg)	undefined
Memory (System)	31.78GB (14.68GB free)
Process Argv	--file-uri file:///c%3A/Users/slademar1/workspaces/sitecore.code-workspace
Screen Reader	no
VM	0%

Extensions (20)

Extension	Author (truncated)	Version
armview	ben	0.3.3
xml	Dot	2.5.0
gitlens	eam	10.2.1
todo-tree	Gru	0.0.169
azure-pipelines	ms-	1.165.1
vscode-azureappservice	ms-	0.16.3
vscode-azurefunctions	ms-	0.21.0
vscode-azurestorage	ms-	0.8.0
vscode-cosmosdb	ms-	0.12.2
vscode-docker	ms-	1.0.0
csharp	ms-	1.21.13
azure-account	ms-	0.8.8
azurecli	ms-	0.5.0
powershell	ms-	2020.3.0
vscode-node-azure-pack	ms-	0.0.10
vscode-typescript-tslint-plugin	ms-	1.2.3
vsonline	ms-	1.0.1736
azurerm-vscode-tools	msa	0.8.4
gulptasks	nic	1.3.1
vscode-scss-formatter	sib	1.4.3