docker: added debug ls before make to debug failing docker hub autobuildA

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Step 5/13 : COPY --chown=build:nogroup . /rgpgfs
---> bc2e86185a76
Step 6/13 : WORKDIR /rgpgfs
Removing intermediate container 6f5e57d5e676
---> 277b8a7e3a65
Step 7/13 : RUN make
---> Running in 2a442551af7f
make: *** No targets specified and no makefile found. Stop.
Removing intermediate container 2a442551af7f
The command '/bin/sh -c make' returned a non-zero code: 2

Dockerfile

@@ -13,6 +13,7 @@ USER build
 
 COPY --chown=build:nogroup . /rgpgfs
 WORKDIR /rgpgfs
+RUN ls -lah
 RUN make