Cannot read property 'suites' of undefined

[amittleider]

Environment data

• VS Code version: 1.30.2
• Extension version (available under the Extensions sidebar): 2019.1.0 (also tried with the previous 2 versions of the extension)
• OS and version: Ubuntu 18.04
• Python version (& distribution if applicable, e.g. Anaconda): Python 3.6
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): venv
• Type of python tests: Nosetests

Running a 'discover unit tests' command on some packages results in an error message

Test Discovery Failed: 
Type Error: Cannot read property 'suites' of undefined

There was another issue that referenced this error (which seemed unrelated). #2255

This error only occurs with one package (the common package) inside my workspace (I have 17 total)

{
	"folders": [
		{
			"path": "apis"
		},
		{
			"path": "backtest"
		},
		{
			"path": "build_scripts"
		},
		{
			"path": "common"
		},
		{
			"path": "core"
		},
		{
			"path": "dataviz"
		},
		{
			"path": "docker"
		},
		{
			"path": "financial_data_contracts"
		},
		{
			"path": "ib"
		},
		{
			"path": "jupyter"
		},
		{
			"path": "live"
		},
		{
			"path": "mkdata"
		},
		{
			"path": "ml"
		},
		{
			"path": "reporting"
		},
		{
			"path": "trading"
		},
		{
			"path": "utils"
		},
		{
			"path": "stats"
		}
	],
	"settings": {}
}

console.ts:134 [Extension Host] Python Extension: displayDiscoverStatus TypeError: Cannot read property 'suites' of undefined
	at module.exports.l.parseNoseTestModuleCollectionResult.t.forEach.t (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:771553)
	at Array.forEach (<anonymous>)
	at l.parseNoseTestModuleCollectionResult (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:770744)
	at module.exports.l.getTestFiles.e.split.forEach (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:770391)
	at Array.forEach (<anonymous>)
	at l.getTestFiles (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:770272)
	at l.parse (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:770090)
	at h.<anonymous> (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:769315)
	at Generator.next (<anonymous>)
	at s (/home/mitt/.vscode/extensions/ms-python.python-2019.1.0/out/client/extension.js:83:768384)
	at <anonymous>
t.log @ console.ts:134
t._logExtensionHostMessage @ extensionHost.ts:453
(anonymous) @ extensionHost.ts:244
emitTwo @ events.js:126
emit @ events.js:214
emit @ internal/child_process.js:772
_combinedTickCallback @ internal/process/next_tick.js:141
_tickCallback @ internal/process/next_tick.js:180
notificationsAlerts.ts:40 Test discovery error, please check the configuration settings for the tests.

vscode_bug.txt

[DonJayamanne]

Duplicate of #4268