Fix private requirements version control

private.txt was under version control.

.gitignore

@@ -2,5 +2,5 @@
 config/
 data-*/
 TODO
-openedx/requirements/private.*
+openedx/requirements/private.txt
 .env

openedx/Dockerfile

@@ -54,8 +54,8 @@ RUN curl -L -o dockerize.tar.gz https://github.com/jwilder/dockerize/releases/do
     && rm dockerize.tar.gz
 
 # Install private requirements as late as possible, so they can be modified frequently
-COPY ./requirements/private.txt /tmp/
-RUN pip install --src ../venv/src -r /tmp/private.txt
+COPY ./requirements/ /tmp/requirements
+RUN touch /tmp/requirements/private.txt && pip install --src ../venv/src -r /tmp/requirements/private.txt
 
 # Copy convenient scripts
 COPY ./bin/docker-entrypoint.sh /usr/local/bin/

openedx/requirements/.gitignore

@@ -0,0 +1 @@
+private.txt

openedx/requirements/README

@@ -0,0 +1,3 @@
+Add your additional requirements, such as xblocks, to private.txt. This file
+is not under version control, which means that your changes will not be
+committed to the upstream repository.

openedx/requirements/private.txt

@@ -1,3 +0,0 @@
-# Add your additional requirements here, such as xblocks. This file is not
-# under version control, which means that your changes will not be committed to
-# the upstream repository.