Curl Local Host Names on macOS Yosemite – How to

I just upgraded from Mavericks to Yosemite, and now curl can't see loopback host names.

Set up a simple http server to test:

$ python -m SimpleHTTPServer
Serving HTTP on 0.0.0.0 port 8000 ...

Now I can hit localhost:8000 in chrome. I can even wget it. But in curl, this happens:

$ curl localhost:8000
curl: (7) Failed to connect to localhost port 8000: Connection refused

However, this works:

$ curl 127.0.0.1:8000

I read this answer about wget proxy settings, but it didn't help, because this works:

$ wget --proxy=off localhost:8000

This is really frustrating, because I have a few different loopback hostnames listed in my /etc/hosts file so I can develop apps locally, and I'm used to debugging them with curl.

I've tried with the version of curl that ships with osx:

$ curl --version
curl 7.37.1 (x86_64-apple-darwin14.0) libcurl/7.37.1 SecureTransport zlib/1.2.5
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smtp smtps telnet tftp
Features: AsynchDNS GSS-Negotiate IPv6 Largefile NTLM NTLM_WB SSL libz

$ curl localhost:8000
curl: (7) Failed to connect to localhost port 8000: Connection refused

$ curl 127.0.0.1 # works

And I've tried compiling curl with brew:

$ /usr/local/Cellar/curl/7.38.0/bin/curl --version
curl 7.38.0 (x86_64-apple-darwin14.0.0) libcurl/7.38.0 SecureTransport zlib/1.2.5
Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtsp smtp smtps telnet tftp
Features: IPv6 Largefile NTLM NTLM_WB SSL libz

$ /usr/local/Cellar/curl/7.38.0/bin/curl localhost:8000
curl: (7) Failed to connect to localhost port 8000: Connection refused

$ /usr/local/Cellar/curl/7.38.0/bin/curl 127.0.0.1:8000 # works