Use re to keep final '\n'

Author: StanFromIreland

Lib/test/test_tools/msgfmt_data/general.json

@@ -1,7 +1,7 @@
 [
     [
         "",
-        "Project-Id-Version: PACKAGE VERSION\nPO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\nLast-Translator: FULL NAME <EMAIL@ADDRESS>\nLanguage-Team: LANGUAGE <[email protected]>\nMIME-Version: 1.0\nContent-Type: text/plain; charset=UTF-8\nContent-Transfer-Encoding: 8bit"
+        "Project-Id-Version: PACKAGE VERSION\nPO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\nLast-Translator: FULL NAME <EMAIL@ADDRESS>\nLanguage-Team: LANGUAGE <[email protected]>\nMIME-Version: 1.0\nContent-Type: text/plain; charset=UTF-8\nContent-Transfer-Encoding: 8bit\n"
     ],
     [
         "\n newlines \n",

Lib/test/test_tools/msgfmt_data/general.mo

@@ -161,10 +161,12 @@ def make(filename, outfile):
                 if not msgid:
                     # Filter out POT-Creation-Date
                     # See issue #131852
-                    msgstr = "\n".join(
-                        line
-                        for line in msgstr.decode(encoding).splitlines()
-                        if not line.startswith("POT-Creation-Date:")
+                    import re
+                    msgstr = re.sub(
+                        r"^POT-Creation-Date:.*(?:\n|$)",
+                        "",
+                        msgstr.decode(encoding),
+                        flags=re.MULTILINE,
                     ).encode(encoding)
 
                     # See whether there is an encoding declaration