[Sqlalchemy-tickets] Issue #4054: percent sign escaping in literal binds (zzzeek/sqlalchemy)

[Michael B. <iss...@bi...>]

New issue 4054: percent sign escaping in literal binds
https://bitbucket.org/zzzeek/sqlalchemy/issues/4054/percent-sign-escaping-in-literal-binds

Michael Bayer:

```
#!python

from sqlalchemy import *

e = create_engine("mysql://scott:tiger@localhost/test", echo=True)

s = select([literal("hi % there")])


compiled = s.compile(
    dialect=e.dialect,
    compile_kwargs=dict(literal_binds=True)
)

assert e.scalar(str(compiled)) == "hi % there"

```


related to #4052 as that makes use of literals.  in addition, comment support should be consistent about its use of literal binds vs. other ad-hoc systems