save _build_ci for some jobs

.gitlab-ci.yml

@@ -62,6 +62,7 @@ before_script:
   - dune printenv --root .
   - dev/tools/check-cachekey.sh
   - dev/tools/list-potential-artifacts.sh > downloaded_artifacts.txt
+  - if [ -d saved_build_ci ]; mv saved_build_ci _build_ci; fi
   - dev/ci/gitlab-section.sh end before_script
 
 # Regular "release" build of Coq, with final installed layout
@@ -193,12 +194,14 @@ before_script:
     - echo CI_TARGETS = ${CI_TARGETS:=${CI_JOB_NAME#*:ci-}}
     - for target in $CI_TARGETS; do dev/ci/ci-wrapper.sh "$target"; done
   after_script:
+    - if [ "$SAVE_BUILD_CI" ] && [ -d _build_ci ]; then mv _build_ci saved_build_ci; fi
     - dev/tools/list-potential-artifacts.sh > available_artifacts.txt
     - dev/tools/cleanup-artifacts.sh downloaded_artifacts.txt available_artifacts.txt
   artifacts:
     name: "$CI_JOB_NAME"
     paths:
       - _install_ci
+      - saved_build_ci
     when: always
     expire_in: 1 week
   needs:
@@ -618,6 +621,7 @@ library:ci-bedrock2:
   extends: .ci-template-flambda
   variables:
     NJOBS: "1"
+    SAVE_BUILD_CI: "1"
   needs:
   - build:edge+flambda
   - library:ci-stdlib+flambda
@@ -734,6 +738,7 @@ library:ci-fiat_crypto:
   extends: .ci-template-flambda
   variables:
     COQEXTRAFLAGS: "-async-proofs-tac-j 0"
+    SAVE_BUILD_CI: "1"
   needs:
   - build:edge+flambda
   - library:ci-stdlib+flambda
@@ -846,6 +851,8 @@ library:ci-mathcomp:
   - library:ci-stdlib+flambda
   - plugin:ci-elpi_hb  # for Hierarchy Builder
   stage: build-2
+  variables:
+    SAVE_BUILD_CI: "1"
 
 library:ci-mathcomp_test:
   extends: .ci-template-flambda
@@ -1102,6 +1109,7 @@ plugin:ci-elpi_hb:
   - library:ci-stdlib+flambda
   variables:
     CI_TARGETS: "elpi hb"
+    SAVE_BUILD_CI: "1"
 
 plugin:ci-elpi_test:
   extends: .ci-template-flambda
@@ -1192,6 +1200,8 @@ plugin:ci-quickchick:
   - plugin:ci-elpi_hb
   - library:ci-mathcomp
   stage: build-3+
+  variables:
+    SAVE_BUILD_CI: "1"
 
 plugin:ci-quickchick_test:
   extends: .ci-template-flambda