diff --git a/ci/test-nightly.sh b/ci/test-nightly.sh
index 7727a20d499c60..4aafa21913ced9 100755
--- a/ci/test-nightly.sh
+++ b/ci/test-nightly.sh
@@ -2,8 +2,21 @@
 set -e
 
 cd "$(dirname "$0")/.."
-source ci/upload-ci-artifact.sh
 
+
+if ci/is-pr.sh; then
+  affectedFiles="$(buildkite-agent meta-data get affected_files)"
+  echo "Affected files in this PR: $affectedFiles"
+  if [[ ! ":$affectedFiles:" =~ \.rs: ]]; then
+    echo "Skipping coverage build as no Rust files were modified"
+    exit 0
+  else
+    echo "Modification to one or more Rust files detected"
+  fi
+fi
+
+
+source ci/upload-ci-artifact.sh
 ci/version-check.sh stable
 export RUST_BACKTRACE=1
 
@@ -25,31 +38,68 @@ cargo_install_unless() {
 
 cargo_install_unless cargo-cov cargo cov --help
 
-# Generate coverage data and report via unit-test suite.
 _ cargo cov clean
 _ cargo cov build --all
-_ cargo cov test --lib
-_ cargo cov report
+_ cargo cov test --all --lib
 _ ./scripts/fetch-grcov.sh
-_ ./grcov . -t lcov > lcov.info
-_ genhtml -o target/cov/report-lcov --show-details --highlight --ignore-errors source --legend lcov.info
 
-# Upload to tarballs to buildkite.
-_ cd target/cov && tar -cjf cov-report.tar.bz2 report/* && cd -
-_ upload-ci-artifact "target/cov/cov-report.tar.bz2"
+echo "--- grcov"
+./grcov . -t lcov  > lcov.info
 
-_ cd target/cov && tar -cjf lcov-report.tar.bz2 report-lcov/* && cd -
-_ upload-ci-artifact "target/cov/lcov-report.tar.bz2"
+echo "--- filter_non_local_files_from_lcov"
+filter_non_local_files_from_lcov() {
+  declare skip=false
+  while read -r line; do
+    if [[ $line =~ ^SF:/ ]]; then
+      skip=true # Skip all absolute paths as these are references into ~/.cargo
+    elif [[ $line =~ ^SF:(.*) ]]; then
+      # Skip relative paths that don't exist
+      declare file="${BASH_REMATCH[1]}"
+      if [[ -r $file ]]; then
+        skip=false
+      else
+        skip=true
+      fi
+    fi
+    [[ $skip = true ]] || echo "$line"
+  done
+}
 
-# Upload coverage files to buildkite for grcov debugging
-#_ cd target/cov/build && tar -cjf cov-gcda.tar.bz2 gcda/* && cd -
-#_ upload-ci-artifact "target/cov/build/cov-gcda.tar.bz2"
-#
-#_ cd target/cov/build && tar -cjf cov-gcno.tar.bz2 gcno/* && cd -
-#_ upload-ci-artifact "target/cov/build/cov-gcno.tar.bz2"
+filter_non_local_files_from_lcov < lcov.info > lcov_local.info
 
+echo "--- codecov.io report"
 if [[ -z "$CODECOV_TOKEN" ]]; then
-  echo CODECOV_TOKEN undefined
+  echo "^^^ +++"
+  echo CODECOV_TOKEN undefined, codecov.io upload skipped
 else
-  bash <(curl -s https://codecov.io/bash) -X gcov
+  bash <(curl -s https://codecov.io/bash) -X gcov -f lcov_info.info
 fi
+
+
+echo "--- html report"
+: "${BUILDKITE_COMMIT:=local}"
+reportName="report-lcov-${BUILDKITE_COMMIT:0:9}"
+
+# Tip: genhtml comes from |brew install lcov| or |apt-get install lcov|
+genhtml \
+  --output-directory target/cov/$reportName \
+  --show-details \
+  --highlight \
+  --ignore-errors source \
+  --legend \
+  --prefix "$PWD" \
+  lcov_local.info
+
+ls -l target/cov/$reportName/index.html
+(
+  set -x
+  cd target/cov
+  tar zcf $reportName.tar.gz $reportName
+)
+_ upload-ci-artifact "target/cov/$reportName.tar.gz"
+
+gzip lcov.info
+_ upload-ci-artifact "lcov.info.gz"
+
+gzip lcov_local.info
+_ upload-ci-artifact "lcov_local.info.gz"