[git] Use "backslashreplace" instead of "surrogateescape".

When decoding as utf8, if the character cannnot be decoded,
use the backslashreplace error handler, instead of the
surrogateescape error handler.

Fixes #18 for git backend, maybe others should be fixed too.

perceval/backends/git.py

@@ -154,7 +154,7 @@ def parse_git_log_from_file(filepath):
         :raises OSError: raised when an error occurs reading the
             given file
         """
-        with open(filepath, 'r', errors='surrogateescape') as f:
+        with open(filepath, 'r', errors='backslashreplace') as f:
             parser = GitParser(f)
 
             for commit in parser.parse():
@@ -648,7 +648,7 @@ def log(self, from_date=None, encoding='utf-8'):
                       self.uri, self.dirpath)
 
         for line in gitlog:
-            line = line.decode(encoding, errors='surrogateescape')
+            line = line.decode(encoding, errors='backslashreplace')
             yield line
 
     @staticmethod
@@ -675,10 +675,10 @@ def _exec(cmd, cwd=None, env=None):
             raise RepositoryError(cause=str(e))
 
         if proc.returncode != 0:
-            err = errs.decode('utf-8', errors='surrogateescape')
+            err = errs.decode('utf-8', errors='backslashreplace')
             cause = "git command - %s" % err
             raise RepositoryError(cause=cause)
         else:
-            logging.debug(errs.decode('utf-8', errors='surrogateescape'))
+            logging.debug(errs.decode('utf-8', errors='backslashreplace'))
 
         return outs

tests/data/git_bad_utf8.txt

@@ -0,0 +1,10 @@
+commit c4c8ea948aa21527d502e87227b2f1d951bc506d d69332b875efb52ea5276d5638ce572fcd7375f2
+Author:     Jason Gaston <[email protected]>
+AuthorDate: Sat Apr 16 15:24:43 2005 -0700
+Commit:     Linus Torvalds <[email protected]>
+CommitDate: Sat Apr 16 15:24:43 2005 -0700
+
+    [PATCH] intel8x0: AC'97 audio patch for Intel ESB2
+
+    Signed-off-by: �Jason Gaston <[email protected]>
+

tests/test_git.py

@@ -204,6 +204,22 @@ def test_git_encoding_error(self):
         self.assertEqual(commit['commit'], 'cb24e4f2f7b2a7f3450bfb15d1cbaa97371e93fb')
         self.assertEqual(commit['message'], 'Calling \udc93Open Type\udc94 (CTRL+SHIFT+T) after startup - performance improvement.')
 
+    def test_git_utf8_error(self):
+        """Characters that cannot decoded as utf8 can be later encoded as utf8.
+
+        This test raised the following exception before being fixed:
+        "UnicodeEncodeError: 'utf-8' codec can't encode character '\udca0'
+        in position 153: surrogates not allowed"
+
+        """
+
+        message_ok = b"[PATCH] intel8x0: AC'97 audio patch for Intel ESB2\n" \
+          + b"\nSigned-off-by: \\xa0Jason Gaston <[email protected]>"
+
+        commits = Git.parse_git_log_from_file("data/git_bad_utf8.txt")
+        commit = [commit for commit in commits][0]
+        self.assertEqual(commit['message'].encode('utf8'), message_ok)
+
     def test_git_parser_from_iter(self):
         """Test if the static method parses a git log from a repository"""