Fix installation of pip with SAGE_SUDO

Author: Matthias Koeppe

build/bin/sage-dist-helpers

@@ -388,7 +388,7 @@ sdh_store_and_pip_install_wheel() {
             local sudo=""
             local root=""
         fi
-        sdh_actually_pip_install_wheel $distname $root $pip_options -r "$SAGE_SPKG_SCRIPTS/$PKG_BASE/spkg-requirements.txt"
+        sdh_actually_pip_install_wheel $distname $root $pip_options "$wheel"
     fi
     echo "sdh_pip_uninstall -r \"\$SAGE_SPKG_SCRIPTS/\$PKG_BASE/spkg-requirements.txt\"" >> "$script_dir"/spkg-piprm
 }
@@ -406,7 +406,7 @@ sdh_actually_pip_install_wheel() {
         echo "(ignoring error)" >&2
     fi
     $sudo sage-pip-install "$@" || \
-        sdh_die "Error installing $@"
+        sdh_die "Error installing $distname"
 }
 
 sdh_pip_uninstall() {

build/pkgs/pip/spkg-install.in

@@ -2,6 +2,10 @@ cd src
 
 sdh_setup_bdist_wheel
 
+# pip can install its own wheel! But first we need to ensure that the pip
+# source directory in on the PYTHONPATH
+export PYTHONPATH="$(pwd)/src"
+
 # --ignore-installed makes sure that pip does not mistake
 # its own source tree as an existing installation
 sdh_store_and_pip_install_wheel --ignore-installed .