Add global safe.directory for CI

src/ci/docker/host-x86_64/armhf-gnu/Dockerfile

@@ -78,6 +78,8 @@ RUN curl -O https://ci-mirrors.rust-lang.org/rustc/vexpress-v2p-ca15-tc1.dtb
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+COPY static/gitconfig /etc/gitconfig
+
 ENV RUST_CONFIGURE_ARGS --qemu-armhf-rootfs=/tmp/rootfs
 ENV SCRIPT python3 ../x.py --stage 2 test --host='' --target arm-unknown-linux-gnueabihf
 

src/ci/docker/host-x86_64/wasm32/Dockerfile

@@ -48,6 +48,8 @@ ENV TARGETS=wasm32-unknown-emscripten
 # Use -O1 optimizations in the link step to reduce time spent optimizing.
 ENV EMCC_CFLAGS=-O1
 
+COPY static/gitconfig /etc/gitconfig
+
 # Emscripten installation is user-specific
 ENV NO_CHANGE_USER=1
 

src/ci/docker/static/gitconfig

@@ -0,0 +1,2 @@
+[safe]
+directory = *

src/ci/run.sh

@@ -11,6 +11,16 @@ if [ "$NO_CHANGE_USER" = "" ]; then
     useradd --shell /bin/bash -u $LOCAL_USER_ID -o -c "" -m user
     export HOME=/home/user
     unset LOCAL_USER_ID
+
+    # Ensure that runners are able to execute git commands in the worktree,
+    # overriding the typical git protections. In our docker container we're running
+    # as root, while the user owning the checkout is not root.
+    # This is only necessary when we change the user, otherwise we should
+    # already be running with the right user.
+    #
+    # For NO_CHANGE_USER done in the small number of Dockerfiles affected.
+    echo -e '[safe]\n\tdirectory = *' > /home/user/gitconfig
+
     exec su --preserve-environment -c "env PATH=$PATH \"$0\"" user
   fi
 fi