chore: add sticky permissions

Author: joseluisq

Dockerfile

@@ -16,7 +16,8 @@ RUN apt-get update && \
         libgmp-dev \
         libxml2-dev \
         nano && \
-    apt-get clean && rm -rf /var/lib/apt/lists/*
+    apt-get clean && rm -rf /var/lib/apt/lists/* && \
+    chmod g+s /home/rust
 
 USER rust
 
@@ -36,8 +37,7 @@ RUN cd /home/rust && \
     https://s3.amazonaws.com/andrew-osx-sdks/MacOSX${OSXCROSS_SDK_VERSION}.sdk.tar.xz && \
     env UNATTENDED=yes OSX_VERSION_MIN=10.7 ./build.sh && \
     rm -rf ./tarballs/MacOSX${OSXCROSS_SDK_VERSION}.sdk.tar.xz && \
-    rm -rf /tmp/* && \
-    chmod g+s /home/rust
+    rm -rf /tmp/*
 
 ENV PATH $PATH:/home/rust/osxcross/target/bin