Debian: move to groupadd/useradd.

Dockerfile-debian.template

@@ -8,8 +8,8 @@ ENV PKG_RELEASE     %%PKG_RELEASE%%
 
 RUN set -x \
 # create nginx user/group first, to be consistent throughout docker variants
-    && addgroup --system --gid 101 nginx \
-    && adduser --system --disabled-login --ingroup nginx --no-create-home --home /nonexistent --gecos "nginx user" --shell /bin/false --uid 101 nginx \
+    && groupadd --system --gid 101 nginx \
+    && useradd --system --gid nginx --no-create-home --home /nonexistent --comment "nginx user" --shell /bin/false --uid 101 nginx \
     && apt-get update \
     && apt-get install --no-install-recommends --no-install-suggests -y gnupg1 ca-certificates \
     && \