curl: make curl_args more configurable.

Allow configuring whether output should be shown or the default the
default user agent is used.

Library/Homebrew/global.rb

@@ -27,14 +27,6 @@ RUBY_BIN = RUBY_PATH.dirname
 HOMEBREW_USER_AGENT_CURL = ENV["HOMEBREW_USER_AGENT_CURL"]
 HOMEBREW_USER_AGENT_RUBY = "#{ENV["HOMEBREW_USER_AGENT"]} ruby/#{RUBY_VERSION}-p#{RUBY_PATCHLEVEL}".freeze
 
-HOMEBREW_CURL_ARGS = [
-  "--fail",
-  "--progress-bar",
-  "--remote-time",
-  "--location",
-  "--user-agent", HOMEBREW_USER_AGENT_CURL
-].freeze
-
 require "tap_constants"
 
 module Homebrew

Library/Homebrew/utils/curl.rb

 require "pathname"
 require "open3"
 
-def curl_args(extra_args = [])
+def curl_args(options = {})
   curl = Pathname.new ENV["HOMEBREW_CURL"]
   curl = Pathname.new "/usr/bin/curl" unless curl.exist?
   raise "#{curl} is not executable" unless curl.exist? && curl.executable?
 
-  flags = HOMEBREW_CURL_ARGS
-  flags -= ["--progress-bar"] if ARGV.verbose?
+  args = [
+    curl.to_s,
+    "--remote-time",
+    "--location",
+  ]
 
-  args = [curl.to_s] + flags + extra_args
-  args << "--verbose" if ENV["HOMEBREW_CURL_VERBOSE"]
-  args << "--silent" if !$stdout.tty? || ENV["TRAVIS"]
+  unless options[:default_user_agent]
+    args << "--user-agent" << HOMEBREW_USER_AGENT_CURL
+  end
+
+  unless options[:show_output]
+    args << "--progress-bar" unless ARGV.verbose?
+    args << "--verbose" if ENV["HOMEBREW_CURL_VERBOSE"]
+    args << "--fail"
+    args << "--silent" if !$stdout.tty? || ENV["TRAVIS"]
+  end
+
+  args += options[:extra_args] if options[:extra_args]
   args
 end
 
 def curl(*args)
-  safe_system(*curl_args(args))
+  safe_system(*curl_args(extra_args: args))
 end
 
 def curl_output(*args)
-  curl_args = curl_args(args)
-  curl_args -= ["--fail", "--silent"]
+  curl_args = curl_args(extra_args: args, show_output: true)
   Open3.popen3(*curl_args) do |_, stdout, stderr, wait_thread|
     [stdout.read, stderr.read, wait_thread.value]
   end