Use a single log message.

src/pip/_internal/collector.py

@@ -521,11 +521,14 @@ class LinkCollector(object):
         ]
 
         url_locations = _remove_duplicate_links(url_locations)
-        logger.debug('%d location(s) to search for versions of %s:',
-                     len(url_locations), project_name)
-
-        for location in url_locations:
-            logger.debug('* %s', location)
+        lines = [
+            '{} location(s) to search for versions of {}:'.format(
+                len(url_locations), project_name,
+            ),
+        ]
+        for link in url_locations:
+            lines.append('* {}'.format(link))
+        logger.debug('\n'.join(lines))
 
         pages_links = {}
         for page in self._get_pages(url_locations):

tests/unit/test_collector.py

@@ -447,8 +447,9 @@ class TestLinkCollector(object):
             'https://pypi.org/abc-1.0.tar.gz#md5=000000000'
         )
 
-        actual = [record_tuple[1:] for record_tuple in caplog.record_tuples]
-        assert actual == [
-            (logging.DEBUG, '1 location(s) to search for versions of twine:'),
-            (logging.DEBUG, '* https://pypi.org/simple/twine/'),
+        expected_message = dedent("""\
+        1 location(s) to search for versions of twine:
+        * https://pypi.org/simple/twine/""")
+        assert caplog.record_tuples == [
+            ('pip._internal.collector', logging.DEBUG, expected_message),
         ]