Use different build/dir for each image

.gitlab-ci.yml

@@ -7,14 +7,14 @@ build:gcc8-seq-coverage:
   image: localhost:5000/ubuntu_gcc8
   stage: build
   script:
-    - mkdir -p build
-    - cd build
-    - CXX=g++-8 CC=gcc-8 cmake .. -DCMAKE_BUILD_TYPE=Coverage
+    - mkdir -p build/gcc8
+    - cd build/gcc8
+    - CXX=g++-8 CC=gcc-8 cmake ../.. -DCMAKE_BUILD_TYPE=Coverage
     - make pugs
   cache:
     key: "${CI_COMMIT_REF_SLUG}-gcc8"
     paths:
-      - build/
+      - build/gcc8
     untracked: true
 
 
@@ -24,27 +24,27 @@ test:gcc8-seq-coverage:
   dependencies:
     - build:gcc8-seq-coverage
   script:
-    - cd build
+    - cd build/gcc8
     - make run_unit_tests
     - make coverage
   cache:
     key: "${CI_COMMIT_REF_SLUG}-gcc8"
     paths:
-      - build/
+      - build/gcc8
     untracked: true
 
 build:clang8-seq-coverage:
   image: localhost:5000/ubuntu_clang8
   stage: build
   script:
-    - mkdir -p build
-    - cd build
-    - CXX=clang++-8 CC=clang-8 cmake .. -DCMAKE_BUILD_TYPE=Coverage -DCLANG_FORMAT=/usr/bin/clang-format-8
+    - mkdir -p build/clang8
+    - cd build/clang8
+    - CXX=clang++-8 CC=clang-8 cmake ../.. -DCMAKE_BUILD_TYPE=Coverage -DCLANG_FORMAT=/usr/bin/clang-format-8
     - make pugs
   cache:
     key: "${CI_COMMIT_REF_SLUG}-clang8"
     paths:
-      - build/
+      - build/clang8
     untracked: true
 
 test:clang8-seq-coverage:
@@ -53,11 +53,11 @@ test:clang8-seq-coverage:
   dependencies:
     - build:clang8-seq-coverage
   script:
-    - cd build
+    - cd build/clang8
     - make run_unit_tests
     - make coverage
   cache:
     key: "${CI_COMMIT_REF_SLUG}-clang8"
     paths:
-      - build/
+      - build/clang8
     untracked: true