Step stage0 to bootstrap from 1.42

[Mark-Simulacrum]

This also includes a commit which fixes the rustfmt downloading logic to redownload when the rustfmt channel changes, and bumps rustfmt to a more recent version.

[pietroalbini]

@bors r+

[bors]

📌 Commit 31dcdc9 has been approved by pietroalbini

[Mark-Simulacrum]

@bors p=1

This bumps the version which is going to be helpful for tracking regressions and so forth, and we also are starting to see PRs that want this to have happened already.

[bors]

⌛ Testing commit 31dcdc9 with merge cc61cb58ec1d4959bd804f5f106d3c23ec860365...

[rust-highfive]

The job dist-powerpc64-linux of 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.

2020-02-04T05:47:49.7837346Z   local time: Tue Feb  4 05:47:49 UTC 2020
2020-02-04T05:47:50.0612348Z   network time: Tue, 04 Feb 2020 05:47:50 GMT
2020-02-04T05:47:50.0614620Z == end clock drift check ==
2020-02-04T05:47:50.9428830Z 
2020-02-04T05:47:50.9518234Z ##[error]Bash exited with code '1'.
2020-02-04T05:47:50.9573912Z ##[section]Starting: Checkout rust-lang/rust@auto to s
2020-02-04T05:47:50.9575619Z ==============================================================================
2020-02-04T05:47:50.9575688Z Task         : Get sources
2020-02-04T05:47:50.9575765Z 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

[Mark-Simulacrum]

@bors r=pietroalbini

[bors]

📌 Commit dbc9894 has been approved by pietroalbini

[bors]

⌛ Testing commit dbc9894 with merge 126ad2b...

[bors]

☀️ Test successful - checks-azure
Approved by: pietroalbini
Pushing 126ad2b to master...