BlenderBIM IFC Git allow branch creation from HEAD

Previously you could only create branches by checking out an older
revision, making changes and committing it. This was an annoyance as
typically you are making changes to the HEAD of a branch, then you
realise this should have been a branch - now you can create the branch
on commit (#3096)

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

@@ -115,18 +115,17 @@ class CommitChanges(bpy.types.Operator):
         repo = IfcGitData.data["repo"]
         if props.commit_message == "":
             return False
-        if (
-            repo
-            and repo.head.is_detached
-            and (
-                not tool.IfcGit.is_valid_ref_format(props.new_branch_name)
-                or props.new_branch_name in [branch.name for branch in repo.branches]
-            )
-        ):
-            cls.poll_message_set(
-                "The new branch name is invalid, please insert a valid branch name (eg. with no spaces, ...)"
-            )
-            return False
+        if repo:
+            if props.new_branch_name in [branch.name for branch in repo.branches]:
+                cls.poll_message_set("Branch already exists!")
+                return False
+            elif not tool.IfcGit.is_valid_ref_format(props.new_branch_name):
+                if repo.head.is_detached:
+                    cls.poll_message_set("Branch name is invalid or empty!")
+                    return False
+                elif props.new_branch_name != "":
+                    cls.poll_message_set("Branch name is invalid!")
+                    return False
         return True
 
     def execute(self, context):

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

@@ -79,10 +79,12 @@ class IFCGIT_PT_panel(bpy.types.Panel):
             row = layout.row()
             row.prop(props, "commit_message")
 
+            row = layout.row()
             if IfcGitData.data["is_detached"]:
-                row = layout.row()
                 row.label(text="HEAD is detached, commit will create a branch", icon="ERROR")
-                row.prop(props, "new_branch_name")
+            else:
+                row.label(text="Optionally create a branch:")
+            row.prop(props, "new_branch_name")
 
             row = layout.row()
             row.operator("ifcgit.commit_changes", icon="GREASEPENCIL")

src/blenderbim/blenderbim/core/ifcgit.py

@@ -27,11 +27,15 @@ def discard_uncommitted(ifcgit, ifc):
 
 
 def commit_changes(ifcgit, ifc, repo):
+    """Commit and create new branches as required"""
     path_ifc = ifc.get_path()
-    ifcgit.git_commit(path_ifc)
 
     if repo.head.is_detached:
+        ifcgit.git_commit(path_ifc)
         ifcgit.create_new_branch()
+    else:
+        ifcgit.checkout_new_branch(path_ifc)
+        ifcgit.git_commit(path_ifc)
 
 
 def add_tag(ifcgit, repo):

src/blenderbim/blenderbim/tool/ifcgit.py

@@ -81,6 +81,16 @@ class IfcGit:
     def git_checkout(cls, path_file):
         IfcGitRepo.repo.git.checkout(path_file)
 
+    @classmethod
+    def checkout_new_branch(cls, path_file):
+        """Create a branch and move uncommitted changes to this branch"""
+        props = bpy.context.scene.IfcGitProperties
+        if props.new_branch_name:
+            IfcGitRepo.repo.git.checkout(b=props.new_branch_name)
+            props.display_branch = props.new_branch_name
+            props.new_branch_name = ""
+            bpy.ops.ifcgit.refresh()
+
     @classmethod
     def git_commit(cls, path_file):
         props = bpy.context.scene.IfcGitProperties