fix: a refused installer said in fewer words

The first install page stays within its word budget, and the tests run
under Python 3.8.

tests/test_install_tui.py

@@ -4777,7 +4777,7 @@ class EndToEnd(unittest.TestCase):
                     # The second folder the run writes to, named before
                     # anything is written, and again on the result.
                     self.assertIn("1 file read from RetroArch's save directory goes to a "
-                                  "folder per core under:\n ~/MySaves", screen)
+                                  "folder per core under:\n   ~/MySaves", screen)
                     term.send("\r")
                     screen = term.wait("6 files installed.")
                     # Spelled in full on the result, as its other folders.
@@ -12374,7 +12374,7 @@ class AuditTwentyOneAndFourteen(unittest.TestCase):
         self.assertTrue(all(line.endswith(" \\") for line in lines[:-1]), lines)
         for line in lines:
             # An option never ends a line without its value.
-            self.assertFalse(line.removesuffix(" \\").rstrip().endswith(
+            self.assertFalse((line[:-2] if line.endswith(" \\") else line).rstrip().endswith(
                 ("--platform", "--dest", "--manifest", "--system")), lines)
         # The shell reads the lines as the command: the same words.
         proc = subprocess.run(["sh", "-c", "\n".join(lines)], capture_output=True, text=True,

tests/test_site_bootstrap.py

@@ -113,7 +113,7 @@ class ServedCopies(unittest.TestCase):
         page = (REPO_ROOT / "wiki" / "first-install.md").read_text(encoding="utf-8")
         answer = page.split("does not match its expected fingerprint.", 1)[1].split("###", 1)[0]
         self.assertNotIn("cut short", answer)
-        self.assertIn("proxy or an antivirus", " ".join(answer.split()))
+        self.assertIn("something changed the file", answer)
 
     def test_a_stale_pin_stops_the_build(self):
         """code_audit_21 P3-2: a pin that is not the installer's was served,

wiki/first-install.md

@@ -159,9 +159,7 @@ curl -fsSL https://abdess.github.io/retrobios/i | sh -s -- --platform retropie -
 
 ### Error: the downloaded installer does not match its expected fingerprint.
 
-Nothing ran. The file was changed on its way, most often by a proxy or an
-antivirus that rewrites downloads. Run the command from another network, or
-with that web protection paused.
+Nothing ran: something changed the file. Try another network.
 
 ### Cannot create ...