runtests: set web.address to localhost Previously, "hg serve" will listen on "", which is not clear which interface it will actually listen on - it could listen on all interfaces (ex. 0.0.0.0 on IPv4). The run-tests.py script only checks "localhost" for available ports. So let's make it the same for "hg serve" by explicitly setting "web.address" to "localhost". This resolves some IPv6 EADDRINUSE errors.

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m test

Do we ever miss a sub-second change?:

  $ for i in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20; do
  >     hg co -qC 0
  >     echo b > a
  >     hg st
  > done
  M a
  M a
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  M a