github: produce better curl error messages. (#441)

* global: add RUBY_TWO global variable.

* test-bot: use RUBY_TWO global variable.

* github: produce better curl error messages.

If we don't know why curl has failed then ensure that the error messages
that it produced are included as part of the user output.

Library/Homebrew/dev-cmd/test-bot.rb

@@ -647,11 +647,9 @@ module Homebrew
       @category = __method__
       return if @skip_homebrew
 
-      ruby_two = RUBY_VERSION.split(".").first.to_i >= 2
-
       if @tap.nil?
         tests_args = []
-        if ruby_two
+        if RUBY_TWO
           tests_args << "--official-cmd-taps"
           tests_args << "--coverage" if ENV["TRAVIS"]
         end
@@ -892,7 +890,7 @@ module Homebrew
 
     ENV["HOMEBREW_DEVELOPER"] = "1"
     ENV["HOMEBREW_SANDBOX"] = "1"
-    ENV["HOMEBREW_RUBY_MACHO"] = "1" if RUBY_VERSION.split(".").first.to_i >= 2
+    ENV["HOMEBREW_RUBY_MACHO"] = "1" if RUBY_TWO
     ENV["HOMEBREW_NO_EMOJI"] = "1"
     ENV["HOMEBREW_FAIL_LOG_LINES"] = "150"
     ENV["HOMEBREW_EXPERIMENTAL_FILTER_FLAGS_ON_DEPS"] = "1"

Library/Homebrew/global.rb

@@ -30,6 +30,7 @@ else
   )
 end
 RUBY_BIN = RUBY_PATH.dirname
+RUBY_TWO = RUBY_VERSION.split(".").first.to_i >= 2
 
 HOMEBREW_USER_AGENT_CURL = ENV["HOMEBREW_USER_AGENT_CURL"]
 HOMEBREW_USER_AGENT_RUBY = "#{ENV["HOMEBREW_USER_AGENT"]} ruby/#{RUBY_VERSION}-p#{RUBY_PATCHLEVEL}"

Library/Homebrew/utils/curl.rb

@@ -1,4 +1,5 @@
 require "pathname"
+require "open3"
 
 def curl_args(extra_args=[])
   curl = Pathname.new ENV["HOMEBREW_CURL"]
@@ -19,6 +20,15 @@ def curl(*args)
 end
 
 def curl_output(*args)
-  curl_args = curl_args(args) - ["--fail"]
-  Utils.popen_read_text(*curl_args)
+  curl_args = curl_args(args)
+  curl_args -= ["--fail"]
+  if RUBY_TWO
+    curl_args -= ["--silent"]
+    Open3.popen3(*curl_args) do |_, stdout, stderr, wait_thread|
+      [stdout.read, stderr.read, wait_thread.value]
+    end
+  else
+    output = Utils.popen_read_text(*curl_args)
+    [output, nil, $?]
+  end
 end

Library/Homebrew/utils/github.rb

@@ -146,7 +146,8 @@ module GitHub
 
       args += ["--dump-header", "#{headers_tmpfile.path}"]
 
-      output, _, http_code = curl_output(url.to_s, *args).rpartition("\n")
+      output, errors, status = curl_output(url.to_s, *args)
+      output, _, http_code = output.rpartition("\n")
       output, _, http_code = output.rpartition("\n") if http_code == "000"
       headers = headers_tmpfile.read
     ensure
@@ -159,8 +160,8 @@ module GitHub
     end
 
     begin
-      if !http_code.start_with?("2") && !$?.success?
-        raise_api_error(output, http_code, headers)
+      if !http_code.start_with?("2") && !status.success?
+        raise_api_error(output, errors, http_code, headers)
       end
       json = Utils::JSON.load output
       if block_given?
@@ -173,7 +174,7 @@ module GitHub
     end
   end
 
-  def raise_api_error(output, http_code, headers)
+  def raise_api_error(output, errors, http_code, headers)
     meta = {}
     headers.lines.each do |l|
       key, _, value = l.delete(":").partition(" ")
@@ -197,7 +198,7 @@ module GitHub
       raise HTTPNotFoundError, output
     else
       error = Utils::JSON.load(output)["message"] rescue nil
-      error ||= output
+      error ||= "curl failed! #{errors}"
       raise Error, error
     end
   end