CI: minor corrections; exclude "buster-backports" and tags.

not-for-changelog

debian/.gitlab-ci.yml

@@ -3,7 +3,8 @@
 include:
   - remote: https://salsa.debian.org/onlyjob/ci/raw/master/onlyjob-ci.yml
 
-## "amd64-unstable" always runs by default followed by lintian.
+## "amd64-unstable+lintian" job always runs by default (except on
+## "buster-backports" branches).
 
 ## Only for arch:all packages:
 binary-indep:
@@ -12,18 +13,27 @@ binary-indep:
 ## Job to check Build-Depends versioning:
 amd64-testing_unstable:
   extends: .build
+  except:
+    - buster-backports
+    - tags
   variables:
     arch: amd64
     dist: testing_unstable
 
 i386-unstable:
   extends: .build
+  except:
+    - buster-backports
+    - tags
   variables:
     arch: i386
     dist: unstable
 
 amd64-experimental:
   extends: .build
+  except:
+    - buster-backports
+    - tags
   variables:
     arch: amd64
     dist: experimental
@@ -31,7 +41,7 @@ amd64-experimental:
 amd64-stable:
   extends: .build
   when: manual
-  allow_failure: false
+  allow_failure: true
   variables:
     arch: amd64
     dist: stable