stage_executor: set avoidLookingCache only if mounting stage

set `avoidLookingCache` to `true` if `--mount` is using a freshly built
stage and not for `additional-build-context`.

Signed-off-by: flouthoc <flouthoc.git@gmail.com>

Author: flouthoc

imagebuildah/stage_executor.go

@@ -1492,7 +1492,7 @@ func (s *StageExecutor) Execute(ctx context.Context, base string) (imgID string,
 			return "", nil, false, err
 		}
 		for _, mountPoint := range stageMountPoints {
-			if mountPoint.DidExecute {
+			if mountPoint.DidExecute && mountPoint.IsStage {
 				avoidLookingCache = true
 			}
 		}

tests/bud.bats

@@ -943,6 +943,34 @@ _EOF
 
 }
 
+@test "build-test use image from cache with --mount and burst when image is changed" {
+  _prefetch alpine
+  local contextdir=${TEST_SCRATCH_DIR}/bud/platform
+  mkdir -p $contextdir
+
+  cat > $contextdir/Containerfile << _EOF
+FROM alpine
+RUN touch firstfile
+_EOF
+
+  run_buildah build $WITH_POLICY_JSON --layers -t source -f $contextdir/Containerfile
+
+  cat > $contextdir/Containerfile2 << _EOF
+FROM alpine
+
+RUN --mount=type=bind,source=.,target=/build,from=source ls /build
+
+_EOF
+
+  run_buildah build $WITH_POLICY_JSON --layers -t source2 -f $contextdir/Containerfile2
+  expect_output --substring "firstfile"
+
+  # Building again must use cache
+  run_buildah build $WITH_POLICY_JSON --layers -t source2 -f $contextdir/Containerfile2
+  expect_output --substring "Using cache"
+  assert "$output" !~ "firstfile"
+}
+
 # Verify: https://github.com/containers/buildah/issues/4572
 @test "build-test verify no dangling containers are left" {
   _prefetch alpine busybox
@@ -1515,6 +1543,30 @@ _EOF
   expect_output --substring "world"
 }
 
+@test "build-with-additional-build-context must use cache if built with layers" {
+  _prefetch alpine
+  local contextdir=${TEST_SCRATCH_DIR}/bud/platform
+  mkdir -p $contextdir
+  echo world > $contextdir/hello
+
+  cat > $contextdir/Containerfile2 << _EOF
+FROM alpine as some-stage
+RUN echo some_text
+
+# hello should get copied since we are giving priority to additional context
+FROM alpine
+RUN --mount=type=bind,from=some-stage,target=/test,z cat /test/hello
+_EOF
+
+  # Additional context for RUN --mount is file on host
+  run_buildah build $WITH_POLICY_JSON --layers --build-context some-stage=$contextdir -t test -f $contextdir/Containerfile2
+  expect_output --substring "world"
+
+  run_buildah build $WITH_POLICY_JSON --layers --build-context some-stage=$contextdir -t test -f $contextdir/Containerfile2
+  expect_output --substring "Using cache"
+  assert "$output" !~ "world"
+}
+
 # Test usage of RUN --mount=from=<name> with additional context is URL and mount source is relative using src
 @test "build-with-additional-build-context and RUN --mount=from=, additional-context is URL and mounted from subdir" {
   _prefetch alpine