debian/lib/python/debian_linux/debian.py: Parse bottom lines of changelog entries

Changelog doesn't currently provide access to the maintainer
name/address and date.  We need this when updating the signed template
changelog.

While we're at it, make sure we don't ignore any important lines.
Anything beginning with exactly zero or one spaces is a top or bottom
line, respectively; anything else is internal text we can ignore.

debian/lib/python/debian_linux/debian.py

@@ -6,7 +6,7 @@ from . import utils
 
 
 class Changelog(list):
-    _rules = r"""
+    _top_rules = r"""
 ^
 (?P<source>
     \w[-+0-9a-z.]+
@@ -25,15 +25,30 @@ class Changelog(list):
 (?P<urgency>
     \w+
 )
+\n
 """
-    _re = re.compile(_rules, re.X)
+    _top_re = re.compile(_top_rules, re.X)
+    _bottom_rules = r"""
+^
+\ --\ 
+(?P<maintainer>
+    \S(?:\ ?\S)*
+)
+\ \ 
+(?P<date>
+    (.*)
+)
+\n
+"""
+    _bottom_re = re.compile(_bottom_rules, re.X)
+    _ignore_re = re.compile(r'^(?:  |\s*\n)')
 
     class Entry(object):
-        __slot__ = 'distribution', 'source', 'version', 'urgency'
+        __slot__ = 'distribution', 'source', 'version', 'urgency', 'maintainer', 'date'
 
-        def __init__(self, distribution, source, version, urgency):
-            self.distribution, self.source, self.version, self.urgency = \
-                distribution, source, version, urgency
+        def __init__(self, **kwargs):
+            for key, value in kwargs.items():
+                setattr(self, key, value)
 
     def __init__(self, dir='', version=None, file=None):
         if version is None:
@@ -45,23 +60,36 @@ class Changelog(list):
                 self._parse(version, f)
 
     def _parse(self, version, f):
-        while True:
-            line = f.readline()
-            if not line:
-                break
-            match = self._re.match(line)
-            if not match:
-                continue
-            try:
-                v = version(match.group('version'))
-            except Exception:
-                if not len(self):
-                    raise
-                v = Version(match.group('version'))
-            self.append(self.Entry(match.group('distribution'),
-                                   match.group('source'), v,
-                                   match.group('urgency')))
+        top_match = None
+        line_no = 0
 
+        for line in f:
+            line_no += 1
+
+            if self._ignore_re.match(line):
+                pass
+            elif top_match is None:
+                top_match = self._top_re.match(line)
+                if not top_match:
+                    raise Exception('invalid top line %d in changelog' % line_no)
+                try:
+                    v = version(top_match.group('version'))
+                except Exception:
+                    if not len(self):
+                        raise
+                    v = Version(top_match.group('version'))
+            else:
+                bottom_match = self._bottom_re.match(line)
+                if not bottom_match:
+                    raise Exception('invalid bottom line %d in changelog' % line_no)
+
+                self.append(self.Entry(distribution=top_match.group('distribution'),
+                                       source=top_match.group('source'),
+                                       version=v,
+                                       urgency=top_match.group('urgency'),
+                                       maintainer=bottom_match.group('maintainer'),
+                                       date=bottom_match.group('date')))
+                top_match = bottom_match = None
 
 class Version(object):
     _version_rules = r"""