`\NUL` values not allowed in the middle of Sqlite texts

[NorfairKing]

I got this test failure in one of my own projects that uses persistent-sqlite:

    -   expected: "h\910325\NULL\1073793\562934"
        but got: "h\910325"

Given that something goes wrong with a null byte, I figured that there was probably something involving C code going wrong.

The tests in persistent:test:test don't test for text values with nulls:

persistent/persistent-test/src/Init.hs

Lines 187 to 195 in a3eed2f

	arbText :: Gen Text
	arbText =
	T.pack
	. filter ((`notElem` forbidden) . generalCategory)
	. filter (<= '\xFFFF') -- only BMP
	. filter (/= '\0') -- no nulls
	. T.unpack
	<$> arbitrary
	where forbidden = [NotAssigned, PrivateUse]

This was supposedly fixed in #310 but when
but when I comment out that line (line 192 in persistent-test/src/Init.hs), I get this test failure in persistent-sqlite:test:test:

       expected: ("text","@\NUL7")
        but got: ("text","@")

While fixing this problem, would it be possible to also remove the other filters for arbText:

before:

arbText :: Gen Text                                                                                                   
arbText =                                                                                                             
     T.pack                                                                                                           
  .  filter ((`notElem` forbidden) . generalCategory)                                                                 
  .  filter (<= '\xFFFF') -- only BMP                                                                                 
  .  filter (/= '\0')     -- no nulls                                                                              
  .  T.unpack                                                                                                         
  <$> arbitrary                                                                                                       
  where forbidden = [NotAssigned, PrivateUse]    

after:

arbText :: Gen Text
arbText = arbitrary

[snoyberg]

See #925