[PATCH 1 of 2] hghave: add a check for unzip(1) that understands symlinks

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1472102752 14400
#      Thu Aug 25 01:25:52 2016 -0400
# Node ID f4d18b053d9d6705057e1dd105201d86667582bb
# Parent  2c715c771805cbb9f18d8c6d787d9f62b08d4bfb
hghave: add a check for unzip(1) that understands symlinks

unzip(1) from the FreeBSD base system does not understand symlinks, so
test-archive-symlinks is busted.

diff --git a/tests/hghave.py b/tests/hghave.py
--- a/tests/hghave.py
+++ b/tests/hghave.py
@@ -573,3 +573,7 @@ def has_hypothesis():
         return True
     except ImportError:
         return False
+
+ at check("unziplinks", "unzip(1) understands and extracts symlinks")
+def unzip_understands_symlinks():
+    return matchoutput('unzip --help', br'Info-ZIP')