fix(remote): allow to raise during push/fetch

Do not swallow non-zero exit status during push and fetch unless
we managed to parse head information.

This behaviour will effetively handle cases were no work was done
due to invalid refspecs or insufficient permissions.

Fixes #271

4 files changed, 18 insertions, 34 deletions

diff --git a/doc/source/changes.rst b/doc/source/changes.rst
index 52d70c0f..35c2f15c 100644
--- a/doc/source/changes.rst
+++ b/doc/source/changes.rst
@@ -7,6 +7,10 @@ Changelog
 * `IndexFile.add()` will now write the index without any extension data by default. However, you may override this behaviour with the new `write_extension_data` keyword argument.
 
   - Renamed `ignore_tree_extension_data` keyword argument in `IndexFile.write(...)` to `ignore_extension_data`
+* If the git command executed during `Remote.push(...)|fetch(...)` returns with an non-zero exit code and GitPython didn't 
+  obtain any head-information, the corresponding `GitCommandError` will be raised. This may break previous code which expected
+  these operations to never raise. However, that behavious is undesirable as it would effectively hide the fact that there 
+  was an error. See `this issue <https://github.com/gitpython-developers/GitPython/issues/271>`_ for more information.
 
 0.3.6 - Features
 ================
diff --git a/git/remote.py b/git/remote.py
index 6a15c9c4..4baa2838 100644
--- a/git/remote.py
+++ b/git/remote.py
@@ -568,7 +568,12 @@ class Remote(LazyMixin, Iterable):
         # end
 
         # We are only interested in stderr here ...
-        finalize_process(proc)
+        try:
+            finalize_process(proc)
+        except Exception:
+            if len(fetch_info_lines) == 0:
+                raise
+        # end exception handler
 
         # read head information
         fp = open(join(self.repo.git_dir, 'FETCH_HEAD'), 'rb')
@@ -601,7 +606,11 @@ class Remote(LazyMixin, Iterable):
             # END exception handling
         # END for each line
 
-        handle_process_output(proc, stdout_handler, progress_handler, finalize_process)
+        try:
+            handle_process_output(proc, stdout_handler, progress_handler, finalize_process)
+        except Exception:
+            if len(output) == 0:
+                raise
         return output
 
     def fetch(self, refspec=None, progress=None, **kwargs):
diff --git a/git/test/test_remote.py b/git/test/test_remote.py
index 8500a295..c419ecee 100644
--- a/git/test/test_remote.py
+++ b/git/test/test_remote.py
@@ -313,8 +313,7 @@ class TestRemote(TestBase):
         self._do_test_push_result(res, remote)
 
         # invalid refspec
-        res = remote.push("hellothere")
-        assert len(res) == 0
+        self.failUnlessRaises(GitCommandError, remote.push, "hellothere")
 
         # push new tags
         progress = TestRemoteProgress()
diff --git a/git/util.py b/git/util.py
index f41f20fb..1147cb53 100644
--- a/git/util.py
+++ b/git/util.py
@@ -16,10 +16,7 @@ import threading
 
 # NOTE:  Some of the unused imports might be used/imported by others.
 # Handle once test-cases are back up and running.
-from .exc import (
-    GitCommandError,
-    InvalidGitRepositoryError
-)
+from .exc import InvalidGitRepositoryError
 
 from .compat import (
     MAXSIZE,
@@ -154,32 +151,7 @@ def get_user_id():
 
 def finalize_process(proc):
     """Wait for the process (clone, fetch, pull or push) and handle its errors accordingly"""
-    try:
-        proc.wait()
-    except GitCommandError:
-        # if a push has rejected items, the command has non-zero return status
-        # a return status of 128 indicates a connection error - reraise the previous one
-        # Everything else will still be parsed and made available through PushInfo flags
-        # Estimated error results look like this:
-        # ```bash
-        # To /var/folders/xp/m48gs2tx2vg95tmtzw7tprs40000gn/T/tmpk5jeBeremote_repo_test_base
-        # !   refs/heads/master:refs/heads/master [rejected] (non-fast-forward)
-        # Done
-        # error: failed to push some refs to
-        # '/var/folders/xp/m48gs2tx2vg95tmtzw7tprs40000gn/T/tmpk5jeBeremote_repo_test_base'
-        # hint: Updates were rejected because the tip of your current branch is behind
-        # hint: its remote counterpart. Integrate the remote changes (e.g.
-        # hint: 'git pull ...') before pushing again.
-        # hint: See the 'Note about fast-forwards' in 'git push --help' for details.
-        # ```
-        # See https://github.com/gitpython-developers/GitPython/blob/master/git/test/test_remote.py#L305
-        # on how to check for these kinds of errors.
-        # Also see this issue for a reason for this verbosity:
-        # https://github.com/gitpython-developers/GitPython/issues/271
-        if proc.poll() == 128:
-            raise
-        pass
-    # END exception handling
+    proc.wait()
 
 #} END utilities