pin pip to a specific version

src/freedombone-utils-search

@@ -674,7 +674,8 @@ function webadmin_install_search {
 
     cat >> "$rootdir/usr/bin/install_searx" <<EOF
 #!/bin/bash
-pip install --upgrade pip
+# see https://github.com/pypa/pip/issues/5240
+pip install --upgrade pip==9.0.3
 
 if ! pip install certifi; then
     echo $'Failed to install certifi'