flake.nix: make sure git dubitious permission error vanishes with docker image using /root .gitconfig considering all dirs as safe dir

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

flake.nix

@@ -139,15 +139,17 @@
             -e ACLOCAL_PATH \
             ${self.devShell.${system}} >/devenv.sh
 
-          # Git configuration for safe directory access.
-          printf '[safe]\n\tdirectory = *\n' >/.gitconfig
           mkdir /tmp; # Temporary directory for various operations.
+          chmod 1777 /tmp
 
           # Ensure /etc/passwd and /etc/group exist with root entries
           echo "root:x:0:0:root:/root:/bin/bash" > /etc/passwd
           echo "root:x:0:" > /etc/group
           mkdir -p /root
           chmod 700 /root
+
+          # Git configuration for safe directory access.
+          echo -e '[safe]\n\tdirectory = *\n' > /root/.gitconfig
         '';
       };
     });