In sdist.prune_file_list, support build.build_base as a pathlib.Path.

Closes #4615

Author: jaraco

distutils/command/sdist.py

@@ -391,7 +391,7 @@ def prune_file_list(self):
         build = self.get_finalized_command('build')
         base_dir = self.distribution.get_fullname()
 
-        self.filelist.exclude_pattern(None, prefix=build.build_base)
+        self.filelist.exclude_pattern(None, prefix=os.fspath(build.build_base))
         self.filelist.exclude_pattern(None, prefix=base_dir)
 
         if sys.platform == 'win32':