[Spec::Lint] Fail gracefully when downloading podspec fails

lib/cocoapods/command/spec/lint.rb

@@ -98,9 +98,13 @@ module Pod
                 require 'cocoapods/open-uri'
                 output_path = podspecs_tmp_dir + File.basename(path)
                 output_path.dirname.mkpath
+                begin
                   open(path) do |io|
                     output_path.open('w') { |f| f << io.read }
                   end
+                rescue => e
+                  raise Informative, "Downloading a podspec from `#{path}` failed: #{e}"
+                end
                 files << output_path
               elsif (pathname = Pathname.new(path)).directory?
                 files += Pathname.glob(pathname + '*.podspec{.json,}')

spec/functional/command/spec_spec.rb

@@ -193,7 +193,7 @@ module Pod
 
     #-------------------------------------------------------------------------#
 
-    describe 'lint subcommand' do
+    describe Command::Spec::Lint do
       it "complains if it can't find any spec to lint" do
         Dir.chdir(temporary_directory) do
           lambda { command('spec', 'lint').run }.should.raise Informative
@@ -214,6 +214,10 @@ module Pod
         end
       end
 
+      it 'fails with an informative error when downloading the podspec 404s' do
+        lambda { run_command('spec', 'lint', 'https://no.such.domain/404') }.should.raise Informative
+      end
+
       before do
         text = (fixture('spec-repos') + 'master/Specs/JSONKit/1.4/JSONKit.podspec.json').read
         text.gsub!(/.*license.*/, '"license": { "file": "LICENSE" },')