Make Patch's allocation pattern more consistent

Duplicate patch's filepaths instead of reusing the memory from the underlying git_patch*.

src/diff.c

@@ -77,8 +77,8 @@ wrap_patch(git_patch *patch)
 
         delta = git_patch_get_delta(patch);
 
-        py_patch->old_file_path = delta->old_file.path;
-        py_patch->new_file_path = delta->new_file.path;
+        py_patch->old_file_path = strdup(delta->old_file.path);
+        py_patch->new_file_path = strdup(delta->new_file.path);
         py_patch->status = git_diff_status_char(delta->status);
         py_patch->similarity = delta->similarity;
         py_patch->flags = delta->flags;
@@ -88,7 +88,6 @@ wrap_patch(git_patch *patch)
         git_patch_line_stats(NULL, &additions, &deletions, patch);
         py_patch->additions = additions;
         py_patch->deletions = deletions;
-        py_patch->patch = patch;
 
         hunk_amounts = git_patch_num_hunks(patch);
         py_patch->hunks = PyList_New(hunk_amounts);
@@ -153,7 +152,8 @@ Patch_dealloc(Patch *self)
     Py_CLEAR(self->hunks);
     Py_CLEAR(self->old_id);
     Py_CLEAR(self->new_id);
-    git_patch_free(self->patch);
+    free(self->old_file_path);
+    free(self->new_file_path);
     PyObject_Del(self);
 }
 

src/types.h

@@ -112,7 +112,6 @@ typedef struct {
     unsigned additions;
     unsigned deletions;
     unsigned flags;
-    git_patch* patch;
 } Patch;
 
 typedef struct {