fixup! Support on the fly patches in easy_install.

Before, the same file name was used for temporary download of several
patches. But download function uses a hard link for a patch using
whose schema is file:, thus download of the second patch broke the
original file of the first patch.

src/zc/buildout/easy_install.py

@@ -1216,11 +1216,11 @@ class Installer:
                 if patch_dict:
                     tag_build += '+%s%03d' % (PATCH_MARKER,
                                               patch_dict['patch_revision'])
-                    for patch in patch_dict['patches']:
+                    for i, patch in enumerate(patch_dict['patches']):
                         url, md5sum = (patch.strip().split('#', 1) + [''])[:2]
                         download = zc.buildout.download.Download()
                         path, is_temp = download(url, md5sum=md5sum or None,
-                                                 path=os.path.join(tmp, 'patch'))
+                                                 path=os.path.join(tmp, 'patch.%s' % i))
                         args = [patch_dict['patch_binary']] + patch_dict['patch_options']
                         kwargs = {'cwd':base,
                                   'stdin':open(path)}