README.md

Error: --with-openssl and --with-libressl are both specified and
curl can only use one at a time.

というエラーが出た時の対処法

$ brew install curl --with-openssl

最後に--with-opensslをつけて、インストール。(--with-libresslでもいいはず)

log.txt

==> Upgrading curl
==> Installing dependencies for curl: pkg-config, libidn, libressl, nghttp2
==> Installing curl dependency: pkg-config
==> Downloading https://homebrew.bintray.com/bottles/pkg-config-0.29.1_1.yosemite.bottle.
######################################################################## 100.0%
==> Pouring pkg-config-0.29.1_1.yosemite.bottle.tar.gz
🍺  /usr/local/Cellar/pkg-config/0.29.1_1: 10 files, 627.3K
==> Installing curl dependency: libidn
==> Downloading https://homebrew.bintray.com/bottles/libidn-1.33.yosemite.bottle.tar.gz
######################################################################## 100.0%
==> Pouring libidn-1.33.yosemite.bottle.tar.gz
==> Caveats
Emacs Lisp files have been installed to:
  /usr/local/share/emacs/site-lisp/libidn
==> Summary
🍺  /usr/local/Cellar/libidn/1.33: 71 files, 1.3M
==> Installing curl dependency: libressl
==> Downloading https://homebrew.bintray.com/bottles/libressl-2.3.6.yosemite.bottle.tar.g
######################################################################## 100.0%
==> Pouring libressl-2.3.6.yosemite.bottle.tar.gz
==> Caveats
A CA file has been bootstrapped using certificates from the system
keychain. To add additional certificates, place .pem files in
  /usr/local/etc/libressl/certs

and run
  /usr/local/opt/libressl/bin/openssl certhash /usr/local/etc/libressl/certs

This formula is keg-only, which means it was not symlinked into /usr/local.

LibreSSL is not linked to prevent conflict with the system OpenSSL.

Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:

    LDFLAGS:  -L/usr/local/opt/libressl/lib
    CPPFLAGS: -I/usr/local/opt/libressl/include

==> Summary
🍺  /usr/local/Cellar/libressl/2.3.6: 1,561 files, 8M
==> Installing curl dependency: nghttp2
==> Downloading https://homebrew.bintray.com/bottles/nghttp2-1.12.0.yosemite.bottle.tar.g
######################################################################## 100.0%
==> Pouring nghttp2-1.12.0.yosemite.bottle.tar.gz
🍺  /usr/local/Cellar/nghttp2/1.12.0: 225 files, 12.5M
==> Installing curl
==> Downloading https://curl.haxx.se/download/curl-7.50.0.tar.bz2
######################################################################## 100.0%
Error: --with-openssl and --with-libressl are both specified and
curl can only use one at a time.

$ brew install curl --with-openssl
==> Downloading https://curl.haxx.se/download/curl-7.50.0.tar.bz2
Already downloaded: /Users/k4zzk/Library/Caches/Homebrew/curl-7.50.0.tar.bz2
==> ./configure --disable-silent-rules --prefix=/usr/local/Cellar/curl/7.50.0 --with-ssl=
==> make install
==> Caveats
This formula is keg-only, which means it was not symlinked into /usr/local.

OS X already provides this software and installing another version in
parallel can cause all kinds of trouble.

Generally there are no consequences of this for you. If you build your
own software and it requires this formula, you'll need to add to your
build variables:

    LDFLAGS:  -L/usr/local/opt/curl/lib
    CPPFLAGS: -I/usr/local/opt/curl/include

==> Summary
🍺  /usr/local/Cellar/curl/7.50.0: 365 files, 2.6M, built in 2 minutes 6 seconds