Revert enabling parallelism by default

[Mark-Simulacrum]

We will re-land a similar patch at a future date but for now we should get a nightly
released in a few hours with the parallel patch, so this should be
reverted to make sure that the next nightly is not parallel-enabled.

r? @ghost

[Mark-Simulacrum]

@bors r+ p=100

This is safe to approve now as we're less than 4 hours from the deadline (3.5ish) and we have another PR currently testing. I've also gone ahead and given this a pretty high priority, but it should be entirely safe to rollup (as it fully reverts a bors merge commit).

[bors]

📌 Commit 7f00a5f has been approved by Mark-Simulacrum

[bors]

🌲 The tree is currently closed for pull requests below priority 100, this pull request will be tested once the tree is reopened

[bors]

⌛ Testing commit 7f00a5f with merge bf3790f9993a067ec56eee5234b9533bba06f720...

[Mark-Simulacrum]

@bors retry yield to rollup including this

[bors]

⌛ Testing commit 7f00a5f with merge 16c58f8f6676336d9b98fdb25563c056fdc35947...

[tmandry]

@bors retry yielding to new rollup (including this)

[bors]

⌛ Testing commit 7f00a5f with merge 2910c49...

[rust-highfive]

Your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-12-18T05:12:49.6266417Z Chocolatey v0.10.15
2019-12-18T05:13:42.1215909Z Installing the following packages:
2019-12-18T05:13:42.1220388Z msys2
2019-12-18T05:13:42.1225904Z By installing you accept licenses for the packages.
2019-12-18T05:15:22.9780668Z Error retrieving packages from source 'https://chocolatey.org/api/v2/':
2019-12-18T05:15:22.9782032Z  Could not connect to the feed specified at 'https://chocolatey.org/api/v2/'. Please verify that the package source (located in the Package Manager Settings) is valid and ensure your network connectivity.
2019-12-18T05:15:22.9787294Z msys2 not installed. The package was not found with the source(s) listed.
2019-12-18T05:15:22.9787946Z  Source(s): 'https://chocolatey.org/api/v2/'
2019-12-18T05:15:22.9788216Z  NOTE: When you specify explicit sources, it overrides default sources.
2019-12-18T05:15:22.9788468Z If the package version is a prerelease and you didn't specify `--pre`,
2019-12-18T05:15:22.9788873Z Please see https://chocolatey.org/docs/troubleshooting for more 
2019-12-18T05:15:22.9789056Z  assistance.
2019-12-18T05:15:22.9891764Z 
2019-12-18T05:15:22.9892218Z Chocolatey installed 0/1 packages. 1 packages failed.
2019-12-18T05:15:22.9892218Z Chocolatey installed 0/1 packages. 1 packages failed.
2019-12-18T05:15:22.9892689Z  See the log for details (C:\ProgramData\chocolatey\logs\chocolatey.log).
2019-12-18T05:15:22.9896605Z 
2019-12-18T05:15:22.9901749Z Failures
2019-12-18T05:15:22.9908427Z  - msys2 - msys2 not installed. The package was not found with the source(s) listed.
2019-12-18T05:15:22.9908914Z  Source(s): 'https://chocolatey.org/api/v2/'
2019-12-18T05:15:22.9909131Z  NOTE: When you specify explicit sources, it overrides default sources.
2019-12-18T05:15:22.9909387Z If the package version is a prerelease and you didn't specify `--pre`,
2019-12-18T05:15:22.9909785Z Please see https://chocolatey.org/docs/troubleshooting for more 
2019-12-18T05:15:22.9909966Z  assistance.
2019-12-18T05:15:23.3434675Z 
2019-12-18T05:15:23.3434675Z 
2019-12-18T05:15:23.3516912Z ##[error]Bash exited with code '1'.
2019-12-18T05:15:23.3638723Z ##[section]Starting: Checkout
2019-12-18T05:15:23.3743650Z ==============================================================================
2019-12-18T05:15:23.3743750Z Task         : Get sources
2019-12-18T05:15:23.3743826Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

[bors]

💔 Test failed - checks-azure

[pietroalbini]

@bors retry

[bors]

⌛ Testing commit 7f00a5f with merge 19bd934...

[bors]

☀️ Test successful - checks-azure
Approved by: Mark-Simulacrum
Pushing 19bd934 to master...