Integration tests: switch some base images

tests/bud.bats

@@ -333,7 +333,7 @@ _EOF
 }
 
 @test "bud build with heredoc content" {
-  _prefetch fedora
+  _prefetch quay.io/fedora/python-311
   run_buildah build -t heredoc $WITH_POLICY_JSON -f $BUDFILES/heredoc/Containerfile .
   expect_output --substring "print first line from heredoc"
   expect_output --substring "print second line from heredoc"
@@ -4486,17 +4486,17 @@ EOM
 }
 
 @test "bud arg and env var with same name" {
-  _prefetch centos:8
+  _prefetch busybox
   # Regression test for https://github.com/containers/buildah/issues/2345
   run_buildah build $WITH_POLICY_JSON -t testctr $BUDFILES/dupe-arg-env-name
   expect_output --substring "https://example.org/bar"
 }
 
 @test "bud copy chown with newuser" {
-  _prefetch ubuntu:latest
+  _prefetch quay.io/fedora/fedora
   # Regression test for https://github.com/containers/buildah/issues/2192
   run_buildah build $WITH_POLICY_JSON -t testctr -f $BUDFILES/copy-chown/Containerfile.chown_user $BUDFILES/copy-chown
-  expect_output --substring "myuser myuser"
+  expect_output --substring "myuser:myuser"
 }
 
 @test "bud-builder-identity" {

tests/bud/build-with-from/Containerfile

@@ -1,4 +1,5 @@
-FROM fedora as builder 
+# "fedora" is replaced as the base image at test-time using the --from flag
+FROM fedora as builder
 FROM busybox
 COPY --from=builder /bin/df /tmp/df_tester
 

tests/bud/copy-chown/Containerfile.chown_user

@@ -1,8 +1,7 @@
-FROM ubuntu:latest
+FROM quay.io/fedora/fedora
 
 ENV MYUSER=myuser
-
 RUN useradd --create-home --home /"${MYUSER}" "${MYUSER}"
 COPY --chown="${MYUSER}" ./copychown.txt /somewhere
 
-RUN ls -alF /somewhere
+RUN stat -c "%U:%G" /somewhere

tests/bud/dupe-arg-env-name/Containerfile

@@ -1,4 +1,4 @@
-FROM centos:8
+FROM busybox
 ARG FOO=bar
 ARG WEBROOT=https://example.org/
 

tests/bud/heredoc/Containerfile

@@ -1,4 +1,7 @@
-FROM fedora
+FROM quay.io/fedora/python-311
+
+USER root
+WORKDIR /
 
 RUN <<EOF
 echo "print first line from heredoc"