SHAFile: Do not trim trailing newlines from extra headers

Some commits contain extra headers with trailing newlines. We need to keep those
intact if we want to be able to round-trip data back to the original.

dulwich/objects.py

@@ -609,6 +609,12 @@ def _parse_message(chunks):
     v = ""
     eof = False
 
+    def _strip_last_newline(value):
+        """Strip the last newline from value"""
+        if value and value.endswith(b'\n'):
+            return value[:-1]
+        return value
+
     # Parse the headers
     #
     # Headers can contain newlines. The next line is indented with a space.
@@ -620,7 +626,7 @@ def _parse_message(chunks):
         else:
             if k is not None:
                 # We parsed a new header, return its value
-                yield (k, v.rstrip(b'\n'))
+                yield (k, _strip_last_newline(v))
             if l == b'\n':
                 # Empty line indicates end of headers
                 break
@@ -632,7 +638,7 @@ def _parse_message(chunks):
         # the text.
         eof = True
         if k is not None:
-            yield (k, v.rstrip(b'\n'))
+            yield (k, _strip_last_newline(v))
         yield (None, None)
 
     if not eof:
@@ -1210,7 +1216,8 @@ class Commit(ShaFile):
                 chunks.append(b' ' + chunk + b'\n')
 
             # No trailing empty line
-            chunks[-1] = chunks[-1].rstrip(b' \n')
+            if chunks[-1].endswith(b' \n'):
+                chunks[-1] = chunks[-1][:-2]
         for k, v in self.extra:
             if b'\n' in k or b'\n' in v:
                 raise AssertionError(

dulwich/tests/test_objects.py

@@ -667,6 +667,39 @@ fDeF1m4qYs+cUXKNUZ03
 =X6RT
 -----END PGP SIGNATURE-----""", c.gpgsig)
 
+    def test_parse_header_trailing_newline(self):
+        c = Commit.from_string(b'''\
+tree a7d6277f78d3ecd0230a1a5df6db00b1d9c521ac
+parent c09b6dec7a73760fbdb478383a3c926b18db8bbe
+author Neil Matatall <oreoshake@github.com> 1461964057 -1000
+committer Neil Matatall <oreoshake@github.com> 1461964057 -1000
+gpgsig -----BEGIN PGP SIGNATURE-----
+ 
+ wsBcBAABCAAQBQJXI80ZCRA6pcNDcVZ70gAAarcIABs72xRX3FWeox349nh6ucJK
+ CtwmBTusez2Zwmq895fQEbZK7jpaGO5TRO4OvjFxlRo0E08UFx3pxZHSpj6bsFeL
+ hHsDXnCaotphLkbgKKRdGZo7tDqM84wuEDlh4MwNe7qlFC7bYLDyysc81ZX5lpMm
+ 2MFF1TvjLAzSvkT7H1LPkuR3hSvfCYhikbPOUNnKOo0sYjeJeAJ/JdAVQ4mdJIM0
+ gl3REp9+A+qBEpNQI7z94Pg5Bc5xenwuDh3SJgHvJV6zBWupWcdB3fAkVd4TPnEZ
+ nHxksHfeNln9RKseIDcy4b2ATjhDNIJZARHNfr6oy4u3XPW4svRqtBsLoMiIeuI=
+ =ms6q
+ -----END PGP SIGNATURE-----
+ 
+
+3.3.0 version bump and docs
+''')
+        self.assertEqual([], c.extra)
+        self.assertEqual(b'''\
+-----BEGIN PGP SIGNATURE-----
+
+wsBcBAABCAAQBQJXI80ZCRA6pcNDcVZ70gAAarcIABs72xRX3FWeox349nh6ucJK
+CtwmBTusez2Zwmq895fQEbZK7jpaGO5TRO4OvjFxlRo0E08UFx3pxZHSpj6bsFeL
+hHsDXnCaotphLkbgKKRdGZo7tDqM84wuEDlh4MwNe7qlFC7bYLDyysc81ZX5lpMm
+2MFF1TvjLAzSvkT7H1LPkuR3hSvfCYhikbPOUNnKOo0sYjeJeAJ/JdAVQ4mdJIM0
+gl3REp9+A+qBEpNQI7z94Pg5Bc5xenwuDh3SJgHvJV6zBWupWcdB3fAkVd4TPnEZ
+nHxksHfeNln9RKseIDcy4b2ATjhDNIJZARHNfr6oy4u3XPW4svRqtBsLoMiIeuI=
+=ms6q
+-----END PGP SIGNATURE-----\n''', c.gpgsig)
+
 
 _TREE_ITEMS = {
     b'a.c': (0o100755, b'd80c186a03f423a81b39df39dc87fd269736ca86'),