Trying to log into GitHub fails with "The user name or passphrase you entered is not correct"

[mattmattmatt]

Prerequisites

• Have you tried to reproduce the problem in Safe Mode? Yes
• Have you followed all applicable steps in the debugging guide? Yes
• Have you checked the FAQs on the message board for common solutions? Yes
• Have you checked that your issue isn't already filed? Yes

Description

Trying to log into GitHub in the "GitHub (preview)" with a generated authentication token fails.

Steps to Reproduce

1. Log out of GitHub
2. Click "Login" in the GitHub panel
3. Have 2FA enabled (not sure if this is related)
4. Generate fresh token
5. Click "Login" after pasting the token.

Expected behavior:

I get logged in.

Actual behavior:

Nothing happens, and the DevTools console throws this error:

Uncaught (in promise) Error: Command failed: security add-generic-password -s atom-github -a https://api.github.com -w 12345SECRETVALIDKEY12345 -U
security: SecKeychainItemModifyContent: The user name or passphrase you entered is not correct.
security: SecKeychainItemCreateFromContent (<default>): The user name or passphrase you entered is not correct.


    at ChildProcess.exithandler (child_process.js:217:12)
    at emitTwo (events.js:106:13)
    at ChildProcess.emit (events.js:194:7)
    at maybeClose (internal/child_process.js:899:16)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)

Reproduces how often:

All of the times

Versions

macOS Sierra, v10.12.6

atom --version
Atom    : 1.25.0
Electron: 1.7.11
Chrome  : 58.0.3029.110
Node    : 7.9.0

apm  1.19.0
npm  3.10.10
node 6.9.5 x64
atom 1.25.0
python 2.7.12
git 2.14.3

Additional Information

I have Two Factor Authentication (2FA) enabled for my account.