(#7886) Add tests and simplify code for continuing on 416

lib/vagrant/util/downloader.rb

@@ -292,14 +292,20 @@ module Vagrant
         # show an error message.
         if result.exit_code != 0
           @logger.warn("Downloader exit code: #{result.exit_code}")
-          parts    = result.stderr.split(/\n*curl:\s+\(\d+\)\s*/, 2)
-          parts[1] ||= ""
-          if parts[1].include? "416"
+          check = result.stderr.match(/\n*curl:\s+\((?<code>\d+)\)\s*(?<error>.*)$/)
+          if check && check[:code] == "416"
             # All good actually. 416 means there is no more bytes to download
+            @logger.warn("Downloader got a 416, but is likely fine. Continuing on...")
           else
+            if !check
+              err_msg = result.stderr
+            else
+              err_msg = check[:error]
+            end
+
             raise Errors::DownloaderError,
               code: result.exit_code,
-              message: parts[1].chomp
+              message: err_msg
           end
         end
 

test/unit/vagrant/util/downloader_test.rb

@@ -41,6 +41,20 @@ describe Vagrant::Util::Downloader do
 
     context "with a bad exit status" do
       let(:exit_code) { 1 }
+      let(:subprocess_result_416) do
+        double("subprocess_result").tap do |result|
+          allow(result).to receive(:exit_code).and_return(exit_code)
+          allow(result).to receive(:stderr).and_return("curl: (416) The download is fine")
+        end
+      end
+
+      it "continues on if a 416 was received" do
+        expect(Vagrant::Util::Subprocess).to receive(:execute).
+          with("curl", *curl_options).
+          and_return(subprocess_result_416)
+
+        expect(subject.download!).to be(true)
+      end
 
       it "raises an exception" do
         expect(Vagrant::Util::Subprocess).to receive(:execute).