url: fix UnicodeDecodeError on certificate verification error
SSLSocket.getpeercert() returns tuple containing unicode for 'subject'.
Since Mercurial does't support IDN at all, it just returns error for non-ascii
certname.
requesting all changes
adding changesets
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adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved