Correctly handle single-byte Content-Range (#1032)

HTTPie previously failed if it continued a download with a single byte left.

httpie/downloads.py

@@ -81,7 +81,7 @@ def parse_content_range(content_range: str, resumed_from: int) -> int:
     # last-byte-pos value, is invalid. The recipient of an invalid
     # byte-content-range- spec MUST ignore it and any content
     # transferred along with it."
-    if (first_byte_pos >= last_byte_pos
+    if (first_byte_pos > last_byte_pos
         or (instance_length is not None
             and instance_length <= last_byte_pos)):
         raise ContentRangeError(

tests/test_downloads.py

@@ -30,6 +30,9 @@ def test_Content_Range_parsing(self):
         assert parse('bytes 100-199/200', 100) == 200
         assert parse('bytes 100-199/*', 100) == 200
 
+        # single byte
+        assert parse('bytes 100-100/*', 100) == 101
+
         # missing
         pytest.raises(ContentRangeError, parse, None, 100)
 
@@ -45,9 +48,6 @@ def test_Content_Range_parsing(self):
         # invalid byte-range-resp-spec
         pytest.raises(ContentRangeError, parse, 'bytes 100-99/199', 100)
 
-        # invalid byte-range-resp-spec
-        pytest.raises(ContentRangeError, parse, 'bytes 100-100/*', 100)
-
     @pytest.mark.parametrize('header, expected_filename', [
         ('attachment; filename=hello-WORLD_123.txt', 'hello-WORLD_123.txt'),
         ('attachment; filename=".hello-WORLD_123.txt"', 'hello-WORLD_123.txt'),