Differences between the toolchain configured by "configure" and the toolchain configured by the "ghc-toolchain" on Ubuntu 16.04.7

Ghc told me to report this, so I duly do. Please ask if any extra context is important. I just checked out and built master branch, then another branch and bam.

https://paste.tomsmeding.com/2c8RQjEx

GHC version used: HEAD

Optional:

Operating System: Ubuntu 16.04.7
System Architecture: amd

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