rpm_ch: Escape \S in regex replacement

Replace the \S in the substitution. Otherwise we fail on Python3.7 like

  ======================================================================
  ERROR: Test determining the author name/email
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "/usr/lib/python3.7/sre_parse.py", line 1021, in parse_template
      this = chr(ESCAPES[this][1])
  KeyError: '\\S'

  During handling of the above exception, another exception occurred:

  Traceback (most recent call last):
    File "/var/scratch/src/git-buildpackage/git-buildpackage/tests/component/rpm/test_rpm_ch.py", line 182, in test_author
      eq_(mock_ch([]), 0)
    File "/var/scratch/src/git-buildpackage/git-buildpackage/tests/component/rpm/test_rpm_ch.py", line 37, in mock_ch
      '--spawn-editor=never'] + args)
    File "/var/scratch/src/git-buildpackage/git-buildpackage/gbp/scripts/rpm_ch.py", line 422, in main
      since = get_start_commit(ch_file.changelog, repo, options)
    File "/var/scratch/src/git-buildpackage/git-buildpackage/gbp/scripts/rpm_ch.py", line 230, in get_start_commit
      since = guess_commit(changelog.sections[0], repo, options)
    File "/var/scratch/src/git-buildpackage/git-buildpackage/gbp/scripts/rpm_ch.py", line 180, in guess_commit
      options.changelog_revision)
    File "/usr/lib/python3.7/re.py", line 192, in sub
      return _compile(pattern, flags).sub(repl, string, count)
    File "/usr/lib/python3.7/re.py", line 309, in _subx
      template = _compile_repl(template, pattern)
    File "/usr/lib/python3.7/re.py", line 300, in _compile_repl
      return sre_parse.parse_template(repl, pattern)
    File "/usr/lib/python3.7/sre_parse.py", line 1024, in parse_template
      raise s.error('bad escape %s' % this, len(this))
  re.error: bad escape \S at position 7

1 files changed, 1 insertions, 1 deletions

diff --git a/gbp/scripts/rpm_ch.py b/gbp/scripts/rpm_ch.py
index 9212f717..9cb99a25 100644
--- a/gbp/scripts/rpm_ch.py
+++ b/gbp/scripts/rpm_ch.py
@@ -176,7 +176,7 @@ def guess_commit(section, repo, options):
     header = section.header
 
     # Try to parse the fields from the header revision
-    rev_re = '^%s$' % re.sub(r'%\((\S+?)\)s', r'(?P<\1>\S+)',
+    rev_re = '^%s$' % re.sub(r'%\((\S+?)\)s', r'(?P<\1>\\S+)',
                              options.changelog_revision)
     match = re.match(rev_re, header['revision'], re.I)
     fields = match.groupdict() if match else {}