remote-hg: the author email can be null

Like 'Foo <>'.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>

contrib/remote-helpers/git-remote-hg

@@ -35,9 +35,9 @@ import urllib
 #
 
 NAME_RE = re.compile('^([^<>]+)')
-AUTHOR_RE = re.compile('^([^<>]+?)? ?<([^<>]+)>$')
-AUTHOR_HG_RE = re.compile('^(.*?) ?<(.+?)(?:>(.+)?)?$')
-RAW_AUTHOR_RE = re.compile('^(\w+) (?:(.+)? )?<(.+)> (\d+) ([+-]\d+)')
+AUTHOR_RE = re.compile('^([^<>]+?)? ?<([^<>]*)>$')
+AUTHOR_HG_RE = re.compile('^(.*?) ?<(.*?)(?:>(.+)?)?$')
+RAW_AUTHOR_RE = re.compile('^(\w+) (?:(.+)? )?<(.*)> (\d+) ([+-]\d+)')
 
 def die(msg, *args):
     sys.stderr.write('ERROR: %s\n' % (msg % args))