runtests: export LOCALIP

Previously, tests hard-code local IP address as "127.0.0.1". That won't work
for IPv6.

This patch exports the $LOCALIP environment variable, which is set to "::1"
if we decide to use IPv6.

tests/run-tests.py

@@ -857,6 +857,12 b' class Test(unittest.TestCase):'
         else:
             return re.escape(p)
 
+    def _localip(self):
+        if self._useipv6:
+            return b'::1'
+        else:
+            return b'127.0.0.1'
+
     def _getenv(self):
         """Obtain environment variables to use during test execution."""
         def defineport(i):
@@ -881,6 +887,10 b' class Test(unittest.TestCase):'
         env["HGENCODINGMODE"] = "strict"
         env['HGIPV6'] = str(int(self._useipv6))
 
+        # LOCALIP could be ::1 or 127.0.0.1. Useful for tests that require raw
+        # IP addresses.
+        env['LOCALIP'] = self._localip()
+
         # Reset some environment variables to well-known values so that
         # the tests produce repeatable output.
         env['LANG'] = env['LC_ALL'] = env['LANGUAGE'] = 'C'