Import pip.Dockerfile into EOL Centos7

Without this a default build fails with:

Usage:
  pip install [options] <requirement specifier> [package-index-options] ...
  pip install [options] -r <requirements file> [package-index-options] ...
  pip install [options] [-e] <vcs project url> ...
  pip install [options] [-e] <local project path> ...
  pip install [options] <archive url/path> ...

no such option: --no-warn-script-location

Updating pip works. But don't want to trigger every other pip builder.

As the Centos7 is EOL, assume this might be the last update,
so just import the working pip.Dockerfile into the centos7.Dockerfile.

.github/workflows/build-centos7.pip-based.yml

@@ -4,15 +4,13 @@ on:
   push:
     paths:
       - 'ci_build_images/centos7.Dockerfile'
-      - 'ci_build_images/pip.Dockerfile'
       - 'ci_build_images/qpress.Dockerfile'
       - 'ci_build_images/buildbot-worker.Dockerfile'
       - .github/workflows/build-centos7.pip-based.yml
       - .github/workflows/bbw_build_container_template.yml
   pull_request:
     paths:
       - 'ci_build_images/centos7.Dockerfile'
-      - 'ci_build_images/pip.Dockerfile'
       - 'ci_build_images/qpress.Dockerfile'
       - 'ci_build_images/buildbot-worker.Dockerfile'
       - .github/workflows/build-centos7.pip-based.yml
@@ -29,7 +27,7 @@ jobs:
             platforms: linux/amd64
     uses: ./.github/workflows/bbw_build_container_template.yml
     with:
-      dockerfile: centos7.Dockerfile pip.Dockerfile
+      dockerfile: centos7.Dockerfile
       image: ${{ matrix.image }}
       platforms: ${{ matrix.platforms }}
     secrets: inherit

ci_build_images/centos7.Dockerfile

@@ -65,3 +65,24 @@ RUN sed -i -e 's/mirrorlist/#mirrorlist/g' \
     && chmod +x /usr/local/bin/dumb-init
 
 ENV WSREP_PROVIDER=/usr/lib64/galera/libgalera_smm.so
+
+# pip.Dockerfile
+# Imported copy as default pip on centos7 doesn't support --no-warn-script-location
+# The pip upgrade would work, but that would needing a customs sles/opensuse build.
+# As Centos7 is EOL, just import it and hopefully no changes.
+
+# Install a recent rust toolchain needed for some arch
+# see: https://cryptography.io/en/latest/installation/
+# then upgrade pip and install BB worker requirements
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs >/tmp/rustup-init.sh \
+    # rust installer does not detect i386 arch \
+    && case $(getconf LONG_BIT) in \
+        "32") bash /tmp/rustup-init.sh -y --default-host=i686-unknown-linux-gnu --profile=minimal ;; \
+        *) bash /tmp/rustup-init.sh -y --profile=minimal ;; \
+    esac \
+    && rm -f /tmp/rustup-init.sh \
+    && source "$HOME/.cargo/env" \
+    && pip3 install --no-cache-dir -U pip \
+    && curl -so /root/requirements.txt \
+       https://raw.githubusercontent.com/MariaDB/buildbot/main/ci_build_images/requirements.txt \
+    && pip3 install --no-cache-dir --no-warn-script-location -r /root/requirements.txt