Fix matching multiline control lines in templates with CRLF line endings

Fixed issue where control statements on multi lines with a backslash would
not parse correctly if the template itself contained CR/LF pairs as on
Windows. Pull request courtesy Charles Pigott.

A missing '\\' meant that it would actually allow

```
% if foo \r
   bar:
```

in a template file and not match if the file actually had a `\r` char

Closes: #346
Pull-request: #346
Pull-request-sha: e79ebab

Change-Id: I179bdd661cecb1ffb3cf262e31183c8e83d98f12
(cherry picked from commit 338b755)

doc/build/unreleased/346.rst

@@ -0,0 +1,9 @@
+.. change::
+    :tags: bug, lexer
+    :tickets: 346
+    :versions: 1.2.0, 1.1.6
+
+    Fixed issue where control statements on multi lines with a backslash would
+    not parse correctly if the template itself contained CR/LF pairs as on
+    Windows. Pull request courtesy Charles Pigott.
+

mako/lexer.py

@@ -443,7 +443,7 @@ def match_expression(self):
 
     def match_control_line(self):
         match = self.match(
-            r"(?<=^)[\t ]*(%(?!%)|##)[\t ]*((?:(?:\\r?\n)|[^\r\n])*)"
+            r"(?<=^)[\t ]*(%(?!%)|##)[\t ]*((?:(?:\\\r?\n)|[^\r\n])*)"
             r"(?:\r?\n|\Z)",
             re.M,
         )

test/test_template.py

@@ -35,6 +35,23 @@ def __exit__(self, *arg):
         pass
 
 
+class MiscTest(TemplateTest):
+    def test_crlf_linebreaks(self):
+
+        crlf = r"""
+<%
+    foo = True
+    bar = True
+%>
+% if foo and \
+     bar:
+     foo and bar
+%endif
+"""
+        crlf = crlf.replace("\n", "\r\n")
+        self._do_test(Template(crlf), "\r\n\r\n     foo and bar\r\n")
+
+
 class EncodingTest(TemplateTest):
     def test_escapes_html_tags(self):
         from mako.exceptions import html_error_template