* revert this. this is not the place to check.

This broke pisi it http://.../.pisi if that package does not
  exist in repo.

  And also if it exists but not the same version, it downloads
  the file twice. Because after downloading sha1sum check does
  not match.

pisi/package.py

@@ -47,12 +47,7 @@ class Package:
         dest = ctx.config.packages_dir()
         self.filepath = join(dest, url.filename())
 
-        sha1sum = None
-        if exists(self.filepath):
-            sha1sum = util.sha1_file(self.filepath)
-
-        name, version = util.parse_package_name(basename(self.filepath))
-        if sha1sum != ctx.packagedb.get_package(name).packageHash:
+        if not exists(self.filepath):
             try:
                 fetch_url(url, dest, ctx.ui.Progress)
             except pisi.fetcher.FetchError: