remove in favour of building via MODPY_PYBUILD + MODPY_BUILD_DIR
(otherwise would need patching anyway)

Index: python/Makefile.in
--- python/Makefile.in.orig
+++ python/Makefile.in
@@ -885,7 +885,6 @@ uninstall-am:
 
 
 @PYTHON_TRUE@python-build:
-@PYTHON_TRUE@	$(PYTHON) -m pip install -e .
 @PYTHON_TRUE@	touch python-build
 
 @PYTHON_TRUE@python-clean:
@@ -895,7 +894,6 @@ uninstall-am:
 @PYTHON_TRUE@distclean: clean
 
 @PYTHON_TRUE@python-install:
-@PYTHON_TRUE@	$(PYTHON) -m pip install --prefix=$(DESTDIR)$(prefix) .
 
 @PYTHON_TRUE@install-exec-local: python-install
 
