Further EUSER and error propagation fixes

This continues auditing all the places where GIT_EUSER is being
returned and making sure to clear any existing error using the
new giterr_user_cancel helper.  As a result, places that relied
on intercepting GIT_EUSER but having the old error preserved also
needed to be cleaned up to correctly stash and then retrieve the
actual error.

Additionally, as I encountered places where error codes were not
being propagated correctly, I tried to fix them up.  A number of
those fixes are included in the this commit as well.

1 files changed, 4 insertions, 9 deletions

diff --git a/src/tree.c b/src/tree.c
index bb59ff82b..8ded007eb 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -884,14 +884,12 @@ static int tree_walk(
 	git_vector_foreach(&tree->entries, i, entry) {
 		if (preorder) {
 			error = callback(path->ptr, entry, payload);
+			if (error < 0)
+				return giterr_user_cancel();
 			if (error > 0) {
 				error = 0;
 				continue;
 			}
-			if (error < 0) {
-				giterr_clear();
-				return GIT_EUSER;
-			}
 		}
 
 		if (git_tree_entry__is_tree(entry)) {
@@ -918,11 +916,8 @@ static int tree_walk(
 			git_buf_truncate(path, path_len);
 		}
 
-		if (!preorder && callback(path->ptr, entry, payload) < 0) {
-			giterr_clear();
-			error = GIT_EUSER;
-			break;
-		}
+		if (!preorder && callback(path->ptr, entry, payload) < 0)
+			return giterr_user_cancel();
 	}
 
 	return error;