distutils/setuptools-native, distutils3/setuptools3-native: do not try to fetch code during do_compile

If a python recipe is using setuptools and the setup_requires argument, where
setuptools will use easy_install to fetch the module if it isn't
present.

The build failed on a machine where a proxy was required, but succeeded on a
machine which had direct access to the internet

Add var-NO_FETCH_BUILD, and set it in distutils_do_compile which does not
allow to fetch code from internet during do_compile.

Example result:
...
ERROR: Do not try to fetch `pytest-runner1' for building. Please add its native recipe to DEPENDS.
Traceback (most recent call last):
  File "setup.py", line 56, in <module>
...

The improvement is flexible for test_requirements argument (used at
`setup.py test'), where use easy_install also.

[YOCTO #12084]
(From OE-Core rev: 57414f4a1c549e6faaa110e6e95ff601b05b7361)

Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/files/0001-conditionally-do-not-fetch-code-by-easy_install.patch

@@ -0,0 +1,34 @@
+From 019422d19c6401fa8f45b1311ecd31bb087c809d Mon Sep 17 00:00:00 2001
+From: Hongxu Jia <hongxu.jia@windriver.com>
+Date: Tue, 17 Jul 2018 10:13:38 +0800
+Subject: [PATCH] conditionally do not fetch code by easy_install
+
+If var-NO_FETCH_BUILD is set, do not allow to fetch code from
+internet by easy_install.
+
+Upstream-Status: Inappropriate [oe specific]
+
+Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
+---
+ setuptools/command/easy_install.py | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/setuptools/command/easy_install.py b/setuptools/command/easy_install.py
+index 85ee40f..7eb9d2a 100755
+--- a/setuptools/command/easy_install.py
++++ b/setuptools/command/easy_install.py
+@@ -637,6 +637,11 @@ class easy_install(Command):
+             os.path.exists(tmpdir) and rmtree(rmtree_safe(tmpdir))
+ 
+     def easy_install(self, spec, deps=False):
++        if os.environ.get('NO_FETCH_BUILD', None):
++            log.error("ERROR: Do not try to fetch `%s' for building. "
++                      "Please add its native recipe to DEPENDS." % spec)
++            return None
++
+         if not self.editable:
+             self.install_site_py()
+ 
+-- 
+2.7.4
+

meta/recipes-devtools/python/python-setuptools.inc

@@ -8,6 +8,8 @@ PYPI_PACKAGE_EXT = "zip"
 
 inherit pypi
 
+SRC_URI_append_class-native = " file://0001-conditionally-do-not-fetch-code-by-easy_install.patch"
+
 SRC_URI[md5sum] = "260630ae1a64bafa39dcc53404d63829"
 SRC_URI[sha256sum] = "012adb8e25fbfd64c652e99e7bab58799a3aaf05d39ab38561f69190a909015f"