RFR: 1101: git webrev for mercurial should ignore config defaults for mercurial commands

[Erik Joelsson]

This patch adds --config defaults.log= to the mercurial command used to resolve a revset to a hash. Since this is a very particular use of the log command, we need to be in full control of all options passed to it.

There are likely several other situations like this that should be fixed, but I would rather not spend the time right now trying to implement a general overhaul for handling all of them.

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Commit messages:
 - SKARA-1101

Changes: https://git.openjdk.java.net/skara/pull/1197/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1197&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1101
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/1197.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1197/head:pull/1197

PR: https://git.openjdk.java.net/skara/pull/1197