BlenderBIM fix Git merge log history (#3096)

The GitPython commit() method isn't suitable for completing a merge as
it only sets one parent, losing all history from the merged branch.

src/blenderbim/blenderbim/bim/module/ifcgit/ui.py

@@ -199,9 +199,9 @@ class COMMIT_UL_List(bpy.types.UIList):
                 refs += "{" + tag.name + "} "
 
         if commit == current_revision:
-            layout.label(text="[HEAD] " + refs + commit.message, icon="DECORATE_KEYFRAME")
+            layout.label(text="[HEAD] " + refs + commit.message.split("\n")[0], icon="DECORATE_KEYFRAME")
         else:
-            layout.label(text=refs + commit.message, icon="DECORATE_ANIMATE")
+            layout.label(text=refs + commit.message.split("\n")[0], icon="DECORATE_ANIMATE")
         layout.label(text=time.strftime("%c", time.localtime(commit.committed_date)))
 
 

src/blenderbim/blenderbim/tool/ifcgit.py

@@ -420,15 +420,12 @@ class IfcGit:
                         operator.report({"ERROR"}, "Unknown IFC Merge failure")
                         return False
 
-            repo.index.add(path_ifc)
-
-            message_summary = repo.git.shortlog(repo.active_branch.name + ".." + props.display_branch)
-            props.commit_message = (
-                "Merge branch '" + props.display_branch + "' into " + repo.active_branch.name + "\n\n" + message_summary
-            )
             props.display_branch = repo.active_branch.name
 
-            cls.git_commit(path_ifc)
+            if os.name == "nt":
+                cls.dos2unix(path_ifc)
+            repo.index.add(path_ifc)
+            repo.git.commit("--no-edit")
             cls.load_project(path_ifc)
             cls.refresh_revision_list(path_ifc)