Use StringIO to write out requirements. Use more common convention of adding...

Use StringIO to write out requirements. Use more common convention of adding newline to each line of the file, not just intervening lines.

setuptools/command/egg_info.py

@@ -5,6 +5,7 @@ Create a distribution's .egg-info directory and contents"""
 import os
 import re
 import sys
+import io
 
 from setuptools import Command
 import distutils.errors
@@ -355,14 +356,21 @@ def warn_depends_obsolete(cmd, basename, filename):
         )
 
 
+def _write_requirements(stream, reqs):
+    lines = yield_lines(reqs or ())
+    append_cr = lambda line: line + '\n'
+    lines = map(append_cr, lines)
+    stream.writelines(lines)
+
 def write_requirements(cmd, basename, filename):
     dist = cmd.distribution
-    data = ['\n'.join(yield_lines(dist.install_requires or ()))]
+    data = io.StringIO()
+    _write_requirements(data, dist.install_requires)
     extras_require = dist.extras_require or {}
     for extra in sorted(extras_require):
-        reqs = extras_require[extra]
-        data.append('\n\n[%s]\n%s' % (extra, '\n'.join(yield_lines(reqs))))
-    cmd.write_or_delete_file("requirements", filename, ''.join(data))
+        data.write('\n[{extra}]\n'.format(**vars()))
+        _write_requirements(data, extras_require[extra])
+    cmd.write_or_delete_file("requirements", filename, data.getvalue())
 
 def write_toplevel_names(cmd, basename, filename):
     pkgs = dict.fromkeys(