Update Bonsai to latest ifcmerge (#7581 #3096)

This version has some functional differences:
- Structured JSON error message instead of free text (on STDOUT not STDERR)
- New --prioritise-local flag to control which side wins in merge conflicts (not used by Bonsai yet)
- IfcLocalPlacement conflicts now auto-resolve instead of failing the merge (partial solution to #6885)
- Float values are normalised when comparing entities (workaround for #7696)

src/bonsai/Makefile

@@ -64,6 +64,7 @@ PYNUMBER:=3$(PYMINOR)
 PYPI_VERSION:=3.$(PYMINOR)
 endif # def PYVERSION
 
+IFCMERGE_VERSION:=2026-04-02
 
 ifdef PLATFORM
 SUPPORTED_PLATFORMS := linux macos macosm1 win
@@ -240,10 +241,9 @@ endif
 
 	# required for three-way git merging
 ifeq ($(PLATFORM), win)
-	cd build/bonsai/libs/bin && wget https://github.com/brunopostle/ifcmerge/releases/download/2025-01-26/ifcmerge.zip
-	cd build/bonsai/libs/bin && unzip ifcmerge.zip && rm ifcmerge.zip
+	cd build/bonsai/libs/bin && wget https://github.com/brunopostle/ifcmerge/releases/download/$(IFCMERGE_VERSION)/ifcmerge.exe
 else
-	cd build/bonsai/libs/bin && wget https://raw.githubusercontent.com/brunopostle/ifcmerge/main/ifcmerge && chmod +x ifcmerge
+	cd build/bonsai/libs/bin && wget https://raw.githubusercontent.com/brunopostle/ifcmerge/$(IFCMERGE_VERSION)/ifcmerge && chmod +x ifcmerge
 endif
 
 	# Generate translations module for Bonsai build

src/bonsai/bonsai/tool/ifcgit.py

@@ -546,7 +546,7 @@ class IfcGit:
             repo.git.mergetool(tool=mergetool)
             return None
         except git.exc.GitCommandError as exc:
-            return re.sub("(  stderr: '|')", "", exc.stderr)
+            return re.sub("(  stdout: '|')", "", exc.stdout)
 
     @classmethod
     def git_merge_abort(cls) -> None: