gh-133197: Improve error message for ft"" and bt"" cases

[sobolevn]

Refs #133197

• Issue: Improve error message for strings with conflicting prefixes #133197

[sobolevn]

Hm, looks like other string prefixes can also conflict with no clear message. Examples:

>>> tb''
  File "<python-input-3>", line 1
    tb''
      ^^
SyntaxError: invalid syntax

>>> fb''
  File "<python-input-0>", line 1
    fb''
      ^^
SyntaxError: invalid syntax

>>> ru''
  File "<python-input-1>", line 1
    ru''
      ^^
SyntaxError: invalid syntax

>>> bu''
  File "<python-input-2>", line 1
    bu''
      ^^
SyntaxError: invalid syntax

Let's handle all t cases here maybe and u-string prefixes in the next PR? It would much easier for me.

[lysnikolaou]

Left a couple of comments inline. Also, it appears that the issue number is wrong. Could you change it please?

[sobolevn]

Now we have prefixes highlighted:

[lysnikolaou]

LGTM! This is a nice improvement! Let's follow up with the rest of the prefixes.