pypi.bbclass: Allow fetching without requiring the hash

This allow the fetching of packages in a backward compatible way[1],
using un-hashed packages.

1. https://bitbucket.org/pypa/pypi/issues/438/backwards-compatible-un-hashed-package

A equivalent fix is available on master in commit 7edad4d (pypi:
update the base pypi url to use the package info without requiring the
hash) so this is really a backport but without unrelated changes.

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Acked-by: Tim Orling (Intel) <ticotimo@gmail.com>
Tested-by: Tim Orling (Intel) <ticotimo@gmail.com>
Acked-by: Armin Kuster <akuster808@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-python/classes/pypi.bbclass

@@ -13,7 +13,7 @@ def pypi_src_uri(d):
     package = d.getVar('PYPI_PACKAGE', True)
     package_ext = d.getVar('PYPI_PACKAGE_EXT', True)
     pv = d.getVar('PV', True)
-    return 'https://pypi.python.org/packages/source/%s/%s/%s-%s.%s' % (package[0], package, package, pv, package_ext)
+    return 'https://files.pythonhosted.org/packages/source/%s/%s/%s-%s.%s' % (package[0], package, package, pv, package_ext)
 
 PYPI_SRC_URI ?= "${@pypi_src_uri(d)}"