[PATCH 1 of 4 V4] hghave: add "absimport" feature to check "absolute_import" in __future__

[FUJIWARA Katsunori]

# HG changeset patch
# User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
# Date 1380902542 -32400
#      Sat Oct 05 01:02:22 2013 +0900
# Node ID 6b27b9c806334c88e3f0190ed345e84dbc8a894d
# Parent  a69a77a80900eabe1257c935818d0910217e9702
hghave: add "absimport" feature to check "absolute_import" in __future__

This patch adds "absimport" feature to check whether "absolute_import"
exists in __future__, which means supporting module loading by
absolute name.

This check is needed for portability of test code using
"absolute_import", because Python earlier than 2.5 doesn't support it.

diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -277,6 +277,11 @@
 def has_aix():
     return sys.platform.startswith("aix")
 
+def has_absimport():
+    import __future__
+    from mercurial import util
+    return util.safehasattr(__future__, "absolute_import")
+
 checks = {
     "true": (lambda: True, "yak shaving"),
     "false": (lambda: False, "nail clipper"),
@@ -318,4 +323,5 @@
     "windows": (has_windows, "Windows"),
     "msys": (has_msys, "Windows with MSYS"),
     "aix": (has_aix, "AIX"),
+    "absimport": (has_absimport, "absolute_import in __future__"),
 }