RFR: git-hg-export: use namespaces for unknown domains

[Erik Helin]

Hi all,

please review this patch that makes `git hg-export` uses namespaces from the census for unknown domains.

Thanks,
Erik

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Commit messages:
 - git-hg-export: use namespaces for unknown domains

Changes: https://git.openjdk.java.net/skara/pull/1122/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1122&range=00
  Stats: 22 lines in 1 file changed: 19 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/skara/pull/1122.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1122/head:pull/1122

PR: https://git.openjdk.java.net/skara/pull/1122