.ci/write-dockerfile.sh: Remove old .git file at the beginning, remov…

…e new .git file at the end

.ci/write-dockerfile.sh

@@ -264,7 +264,7 @@ cat <<EOF
 
 FROM with-system-packages as bootstrapped
 #:bootstrapping:
-RUN rm -rf /new
+RUN rm -rf /new /sage/.git
 $ADD Makefile VERSION.txt COPYING.txt condarc.yml README.md bootstrap bootstrap-conda configure.ac sage .homebrew-build-env tox.ini Pipfile.m4 .gitignore /new/
 $ADD config/config.rpath /new/config/config.rpath
 $ADD src/doc/bootstrap /new/src/doc/bootstrap
@@ -348,7 +348,7 @@ RUN cd /new && rm -rf .git && \
         mv src /sage/src;                                    \
         cd /sage && ./bootstrap && ./config.status;          \
     fi; \
-    cd /sage && rm -rf /new
+    cd /sage && rm -rf /new .git
 
 ARG TARGETS="build"
 $RUN $CHECK_STATUS_THEN make SAGE_SPKG="sage-spkg -y -o" \${USE_MAKEFLAGS} \${TARGETS} $ENDRUN $THEN_SAVE_STATUS