Remove writable group file due to issues with being able to give su access...

Remove writable group file due to issues with being able to give su access when shouldn't be allowed.

base-notebook/Dockerfile

@@ -50,7 +50,7 @@ ADD fix-permissions /usr/local/bin/fix-permissions
 RUN useradd -m -s /bin/bash -N -u $NB_UID $NB_USER && \
     mkdir -p $CONDA_DIR && \
     chown $NB_USER:$NB_GID $CONDA_DIR && \
-    chmod g+w /etc/passwd /etc/group && \
+    chmod g+w /etc/passwd && \
     fix-permissions $HOME && \
     fix-permissions $CONDA_DIR
 

base-notebook/start.sh

@@ -94,8 +94,7 @@ else
         # User is not attempting to override user/group via environment
         # variables, but they could still have overridden the uid/gid that
         # container runs as. Check that the user has an entry in the passwd
-        # file and if not add an entry. Also add a group file entry if the
-        # uid has its own distinct group but there is no entry.
+        # file and if not add an entry.
         whoami &> /dev/null || STATUS=$? && true
         if [[ "$STATUS" != "0" ]]; then
             if [[ -w /etc/passwd ]]; then
@@ -104,11 +103,6 @@ else
                 echo "jovyan:x:$(id -u):$(id -g):,,,:/home/jovyan:/bin/bash" >> /tmp/passwd
                 cat /tmp/passwd > /etc/passwd
                 rm /tmp/passwd
-                id -G -n 2>/dev/null | grep -q -w $(id -u) || STATUS=$? && true
-                if [[ "$STATUS" != "0" && "$(id -g)" == "0" ]]; then
-                    echo "Adding group file entry for $(id -u)"
-                    echo "jovyan:x:$(id -u):" >> /etc/group
-                fi
             else
                 echo 'Container must be run with group "root" to update passwd file'
             fi