fix(hooks): treat only backslash-LF as a line continuation in a commit message

Bash removes a backslash before a newline, but not one before a carriage return. Removing backslash-CRLF joined two lines of the message, and their text was then read as the subject.

scripts/hooks/pre-bash-commit-quality.js

@@ -206,7 +206,7 @@ function validateCommitMessage(command) {
     : null;
   // In double quotes, Bash drops the backslash before $ ` " \ and drops a backslash-newline,
   // a line continuation, altogether. Before any other character the backslash stays.
-  const doubleQuoted = messageMatch[1]?.replace(/\\(\r?\n|[$`"\\])/g, (escape, next) => (next.endsWith('\n') ? '' : next));
+  const doubleQuoted = messageMatch[1]?.replace(/\\([\n$`"\\])/g, (escape, next) => (next === '\n' ? '' : next));
   const message = heredoc ?? doubleQuoted ?? messageMatch[2] ?? messageMatch[3];
   // The format rules apply to the subject: git drops leading blank lines and trailing
   // whitespace, and the first line left is the subject.

tests/hooks/pre-bash-commit-quality.test.js

@@ -531,7 +531,9 @@ if (test('drops a line continuation from a double-quoted message, as Bash does',
   assert.deepStrictEqual(res.issues, []);
   // An escaped backslash before a newline is one backslash, and the newline stays
   assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: path C:\\\\\nbody"').message, 'fix: path C:\\\nbody');
-  // Bash removes the backslash only before $ ` " \ and a newline
+  // Bash removes the backslash only before $ ` " \ and a newline; before a CR it stays
+  assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: keep path\\\r\nbody."').message, 'fix: keep path\\\r\nbody.');
+  assert.deepStrictEqual(hook.validateCommitMessage('git commit -m "fix: keep path\\\r\nbody."').issues, []);
   assert.strictEqual(hook.validateCommitMessage('git commit -m "fix: cost \\$5 in \\d+ steps"').message, 'fix: cost $5 in \\d+ steps');
 })) passed++; else failed++;