Steps to Reproduce:
Does this issue occur when all extensions are disabled?: Yes
1.40.0-insider (72bc289d32ec4f867e73b7f1f2a22f7d614ae2bb)

1.38.1 (b37e54c98e1a74ba89e03073e5a3761284e3ffb0)

git checkout 13dc6f18ac5988cfdac285dd76c0232b1378b2dc
works fine
git checkout 3a626d89a0916c1a478c8fac8b076d6b7dd87ca4
seems to be broken
@yamachu thanks for bisecting.
3a626d89a0916c1a478c8fac8b076d6b7dd87ca4 was authered by @jrieken thus assigning to him
Yup, this is bad:

Though it only happens on auto suggest, not manual trigger.
I've merged the fix by @yamachu: thanks a lot for that!
We'll get the fixed Insiders build next Monday morning CET. Sorry for the disturbance everyone!
Thanks everyone!
Still seeing this pretty consistently on
Version: 1.40.0-insider (user setup)
Commit: 3f6ed25939b8ef157a7a41e0dc43b517898d4005
Date: 2019-10-15T05:26:38.861Z
Electron: 6.0.12
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Windows_NT x64 10.0.18362

Unless this is now the correct behavior? In which case, how do I stop it and get it to insert as before, not replace? 馃槵
@jrieken I'm seeing weird behavior on quotes as well. if you type inside "", the last quote is removed, like in tsconfig.json:
"includes": [
"./" // << Ctrl + Space here
]
becomes
"includes": [
"./server.ts
]
Version: 1.40.0-insider (user setup)
Commit: 3f6ed25939b8ef157a7a41e0dc43b517898d4005
Date: 2019-10-15T05:26:38.861Z
Electron: 6.0.12
Chrome: 76.0.3809.146
Node.js: 12.4.0
V8: 7.6.303.31-electron.0
OS: Windows_NT x64 10.0.17763
@pocesar What language is that?
Oh, I see tsconfig.json. Yeah, that's very likely because JSON uses a more than bogous word definition
@pocesar I have created https://github.com/microsoft/vscode/issues/82666 and I aiming to push a fix today
What's the correct behavior here? If replacing the text is correct, that's fine, but if the current solution is going to be a whack-a-mole fix for each language maybe there's something else that should be done.
Another example. On this one, the comma is removed:

@OfficerHalf We appreciate constructive feedback, if you want to report an issue then please file a new issue, stating the version of vscode, the language, and exact repo steps.
It's not a different issue though, this one just isn't fixed regardless of my preference for replace vs insert. If you'd prefer, I can open a new one.
Things seem to be working in the latest insiders. I'm no longer able to repro @OfficerHalf's issue--can you confirm that this still occurs on the latest build of insiders?

Yeah I haven't noticed any weird behavior in the past few days. I'll certainly comment here if I see it again.
Most helpful comment
I've merged the fix by @yamachu: thanks a lot for that!
We'll get the fixed Insiders build next Monday morning CET. Sorry for the disturbance everyone!