Allow ':' as the first character of a value

The regular expression that matched keys was too loose, so things like

  Foo: : bar

would get parsed as

  {'Foo:': 'bar'}

instead of the correct value (which is also returned by both apt_pkg and
the email package),

  {'Foo': ': bar'}

Closes: #597249

(cherry picked from commit 86ddf35b)

debian/changelog

+python-debian (0.1.18+squeeze1) stable; urgency=low
+
+  * Allow ':' as the first character of a value.  This fixes an
+    implementation error where the paragraph
+
+      Foo: : bar
+
+    would be interpreted as
+
+      {'Foo:': 'bar'}
+
+    by the Python-native parser, while it would be correctly interpreted
+    as
+
+      {'Foo': ': bar'}
+
+    by both the apt_pkg parser and the Python email library.
+    (Closes: #597249)
+
+ -- John Wright <jsw@debian.org>  Wed, 28 Dec 2011 14:50:57 -0800
+
 python-debian (0.1.18) unstable; urgency=low
 
   * Support installation together with older versions of python-apt.

lib/debian/deb822.py

@@ -317,9 +317,11 @@ class Deb822(Deb822Dict):
     ###
 
     def _internal_parser(self, sequence, fields=None):
-        single = re.compile("^(?P<key>\S+)\s*:\s*(?P<data>\S.*?)\s*$")
-        multi = re.compile("^(?P<key>\S+)\s*:\s*$")
-        multidata = re.compile("^\s(?P<data>.+?)\s*$")
+        # The key is non-whitespace, non-colon characters before any colon.
+        key_part = r"^(?P<key>[^: \t\n\r\f\v]+)\s*:\s*"
+        single = re.compile(key_part + r"(?P<data>\S.*?)\s*$")
+        multi = re.compile(key_part + r"$")
+        multidata = re.compile(r"^\s(?P<data>.+?)\s*$")
 
         wanted_field = lambda f: fields is None or f in fields
 

tests/test_deb822.py

@@ -726,6 +726,15 @@ Description: python modules to work with Debian-related data formats
             self.assertEqual(p2['uploaders'],
                              u'Frank Küster <frank@debian.org>')
 
+    def test_bug597249_colon_as_first_value_character(self):
+        """Colon should be allowed as the first value character. See #597249.
+        """
+
+        data = 'Foo: : bar'
+        parsed = {'Foo': ': bar'}
+        self.assertWellParsed(deb822.Deb822(data), parsed)
+
+
 class TestPkgRelations(unittest.TestCase):
 
     def test_packages(self):