Rollup of 7 pull requests#68975

Merged

bors merged 18 commits intorust-lang:masterfrom

Dylan-DPC-zz:rollup-jzab8oh

Feb 9, 2020

Commits on Feb 4, 2020

Fix and test implementation of BTreeMap's first_entry, last_entry, pop_first, pop_last
ssomers
committed

Commits on Feb 5, 2020

Reorder declarations of Result::export/unwrap to match Option
brson
committed
Reorder declarations of Result::expect_err/unwrap_err to match Option
brson
committed

Commits on Feb 7, 2020

Don't use the word 'unwrap' to describe core unwrapping functions
brson
committed

Commits on Feb 8, 2020