Use deep copy of release_version object

Release version is modified again, when calling create_bump_version on it.

release_mixin.py

@@ -1,3 +1,4 @@
+import copy
 from ddadevops import DevopsBuild
 from ddadevops import execute
 from ddadevops import gopass_field_from_path, gopass_password_from_path
@@ -31,11 +32,13 @@ class ReleaseMixin(DevopsBuild):
         self.version_repo = VersionRepository(self.file)
         self.release_version = None
         self.bump_version = None
+        self.commit_string = None
 
     def init(self):
         init_service = InitReleaseService(self.version_repo)
-        self.release_version = init_service.create_release_version()
-        self.bump_version = self.release_version.create_bump_version()
+        self.release_version = init_service.create_release_version(self.commit_string)
+        release_version_copy = copy.deepcopy(self.release_version) # otherwise we'll modify the release_version again
+        self.bump_version = release_version_copy.create_bump_version()        
 
     def prepare(self, version):
         git_repository = GitRepository()