Changed the way the output filename is generated

When ``--download`` without ``--output`` results in a redirect,
now only the initial URL is considered, not the final one.

tests/test_downloads.py

@@ -1,4 +1,5 @@
 import os
+import tempfile
 import time
 
 import pytest
@@ -22,6 +23,7 @@ class Response(object):
 
 
 class TestDownloadUtils:
+
     def test_Content_Range_parsing(self):
         parse = parse_content_range
 
@@ -166,3 +168,15 @@ class TestDownloads:
             downloader.finish()
             assert downloader.interrupted
             downloader._progress_reporter.join()
+
+    def test_download_with_redirect_original_url_used_for_filename(self, httpbin):
+        # Redirect from `/redirect/1` to `/get`.
+        expected_filename = '1.json'
+        orig_cwd = os.getcwd()
+        os.chdir(tempfile.mkdtemp(prefix='httpie_download_test_'))
+        try:
+            assert os.listdir('.') == []
+            http('--download', httpbin.url + '/redirect/1')
+            assert os.listdir('.') == [expected_filename]
+        finally:
+            os.chdir(orig_cwd)