Error: Calling 'fails_with :clang' with 'build' &glt; 600 is disabled! aThere is no replacement

The problem show, when install gnupg.

the detail error:

Error: Calling 'fails_with :clang' with 'build' < 600 is disabled! There is no replacement.
Please report this to the homebrew/core tap:
  /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/python.rb:36

the solution:

first, open terminal, run

brew update-reset

then 

brew update

 note do not change your network, when run brew update-reset, or will output blow error

error: RPC failed; curl 18 transfer closed with outstanding read data remaining
fatal: The remote end hung up unexpectedly
fatal: early EOF
fatal: index-pack failed

references:

1. https://github.com/Homebrew/homebrew-core/issues/36802

2. https://stackoverflow.com/questions/38618885/error-rpc-failed-curl-transfer-closed-with-outstanding-read-data-remaining

3. https://www.jianshu.com/p/631e63dab0a0