[leaf] Request to merge bug fix to master for 1.75 release

From: Emil Dotchevski (emildotchevski_at_[hidden])
Date: 2020-11-24 20:02:07

I'm requesting permission to merge a bug fix by vector-of-bool in LEAF
which makes it work correctly with std::system_error:
https://github.com/boostorg/leaf/pull/15/commits/efc56d1c703777fea4fef2bd24ffb0a91edd64b3

(There is a minor related change on top of this PR, but this bug fix is the
important change in behavior. Note that LEAF is a new library in 1.75).