Do not hide issues.

Even if this snippet was copied from code which hide all exceptions, do not
hide.

src/zc/buildout/download.py

@@ -138,8 +138,6 @@ class Download(object):
                     raise ChecksumError(
                         'MD5 checksum mismatch for cached download '
                         'from %r at %r' % (url, cached_path))
-                except Exception:
-                    pass
             self.logger.debug('Using cache file %s' % cached_path)
         else:
             self.logger.debug('Cache miss; will cache %s as %s' %