sagemathgh-38029: Fix interaction of # 32-bit / # 64-bit tag with blo…

…ck-scoped doctest tags

    
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- Fixes sagemath#36099

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URL: sagemath#38029
Reported by: Matthias Köppe
Reviewer(s):

src/sage/doctest/sources.py

@@ -65,7 +65,7 @@
 find_prompt = re.compile(r"^(\s*)(>>>|sage:)(.*)")
 
 # For testing that enough doctests are created
-sagestart = re.compile(r"^\s*(>>> |sage: )\s*[^#\s]")
+sagestart = re.compile(r"^(\s*(>>> |sage: ))\s*[^#\s]")
 untested = re.compile("(not implemented|not tested)")
 
 # For parsing a PEP 0263 encoding declaration
@@ -331,9 +331,11 @@ def _create_doctests(self, namespace, tab_okay=None):
                             continue
                         else:
                             line = line[:bitness.start()] + "\n"
-                    if self.line_shift and sagestart.match(line):
-                        # We insert blank lines to make up for the removed lines
-                        doc.extend(["\n"]*self.line_shift)
+                    if self.line_shift and (m := sagestart.match(line)):
+                        # We insert empty doctest lines to make up for the removed lines
+                        indent_and_prompt = m.group(1)
+                        doc.extend([indent_and_prompt + "# inserted to compensate for removed conditional doctest output\n"]
+                                   * self.line_shift)
                         self.line_shift = 0
                     doc.append(line)
                     unparsed_doc = True