add python shebang fixer to makefile

Makefile.in

@@ -16,21 +16,28 @@ DESTDIR ?=
 USERINSTALL ?= xfalse
 FLATPAK ?= xfalse
 
+# Define the Python interpreter to use
+PYTHON_INTERPRETER = /usr/bin/python3
 
 .PHONY: all
 ifeq ($(FLATPAK), xtrue)
-all: version umu umu-launcher
+all: version umu umu-launcher fix_shebangs
 else
-all: version umu umu-docs umu-launcher
+all: version umu umu-docs umu-launcher fix_shebangs
 endif
 
 .PHONY: install
 ifeq ($(USERINSTALL), xtrue)
-install: umu-install umu-launcher-install user-install
+install: umu-install umu-launcher-install user-install fix_shebangs
 else
-install: umu-install umu-launcher-install
+install: umu-install umu-launcher-install fix_shebangs
 endif
 
+fix_shebangs:
+	$(info :: Fixing shebangs... )
+	find . -type f -name "*.py" -exec sed -i '1s|^#!/usr/bin/python|#!$(PYTHON_INTERPRETER)|' {} \;
+	find . -type f -name "*.py" -exec sed -i '1s|^#!/usr/bin/env python|#!/usr/bin/env python3|' {} \;
+
 # Special case, do this inside the source directory for release distribution
 umu/umu_version.json: umu/umu_version.json.in
 	$(info :: Updating $(@) )