Patch the baseline test new-year race condition. Fix getnikola#3723.

.gitignore

@@ -5,7 +5,10 @@
 tmp/
 cache/
 output/
+baseline/
+nikola-baseline-build/
 /tags
+v3.*.zip.*
 
 # GitHub token
 .pypt/gh-token

scripts/baseline.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
+
+set -e -o pipefail -x
+
 PYVER=$(scripts/getpyver.py short)
 if [[ "$1" == "check" ]]; then
     echo -e "\033[36m>> Downloading baseline for $PYVER...\033[0m"
@@ -19,8 +22,38 @@ rm "pages/creating-a-theme.rst" "pages/extending.rst" "pages/internals.rst" "pag
 LC_ALL='en_US.UTF-8' PYTHONHASHSEED=0 nikola build --invariant
 if [[ "$1" == "check" ]]; then
     echo -e "\033[36m>> Testing baseline...\033[0m"
-    diff -ubwr ../baseline output
-    if [[ $? == 0 ]]; then
+    python3 -c '
+# In-place edit of copyright notes to adjust the copyright year.
+import time
+YEAR = str(time.gmtime().tm_year)
+for edit_me in [
+        "../baseline/rss.xml",
+        "../baseline/index.html",
+        "../baseline/galleries/index.html",
+        "../baseline/galleries/demo/index.html",
+        "../baseline/listings/index.html",
+        "../baseline/listings/hello.py.html",
+        "../baseline/listings/__pycache__/index.html",
+        "../baseline/pages/about-nikola/index.html",
+        "../baseline/pages/bootstrap-demo/index.html",
+        "../baseline/pages/dr-nikolas-vendetta/index.html",
+        "../baseline/pages/listings-demo/index.html",
+        "../baseline/pages/quickref/index.html",
+        "../baseline/pages/quickstart/index.html",
+        "../baseline/posts/welcome-to-nikola/index.html",
+    ]:
+    with open(edit_me, "rt+") as rssf:
+        rss = rssf.read()
+        copyright_prelude = "Contents © "
+        copyright_prelude_position = rss.find(copyright_prelude)
+        if -1 == copyright_prelude_position:
+            raise RuntimeError(f"Could not find copyright note in {edit_me}")
+        copyright_position = copyright_prelude_position + len(copyright_prelude)
+        new_rss = rss[:copyright_position] + YEAR + rss[copyright_position+4:]
+        rssf.seek(0, 0)
+        rssf.write(new_rss)
+    '
+    if diff -ubwr ../baseline output; then
         echo -e "\033[32;1m>> Baseline test successful\033[0m"
     else
         CODE=$?