tests: handle Message-Id email header possible wrapping
The "Message-Id" header will get wrapped with a new line when exceeding
75 characters on Python 3 (see changeset 7d4f2e4899c5 introducing usage
of email.header.Header.encode and respective doc). This will occur in an
unpredictable manner depending on the hostname's length. To make the
test output consistent across Python versions and hostname
configuration, we add a filter to unwrap this header value.
$ hg init
$ echo 123 > a
$ hg add a
$ hg commit -m "first" a
$ mkdir sub
$ echo 321 > sub/b
$ hg add sub/b
$ hg commit -m "second" sub/b
$ cat sub/b
321
$ hg co 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cat sub/b 2>/dev/null || echo "sub/b not present"
sub/b not present
$ test -d sub || echo "sub not present"
sub not present