Re-add faster replace

[malmaud]

This is the part of #11898 that was inadvertently clobbered by the string refactoring.

[pao]

cc @tkelman I'd just commit this but for the AV failure, let's make sure it's nothing serious first.

[malmaud]

here's the appveyor error, for reference

1 file(s) copied.
cd test && ..\usr\bin\julia runtests.jl all
     * linalg1              in  70.06 seconds
     * linalg2              in  15.79 seconds
     * linalg3              in   8.80 seconds
     * linalg4              in   4.12 seconds
     * linalg/lapack        in   8.12 seconds
     * linalg/triangular    in  62.46 seconds
     * linalg/tridiag       in   2.96 seconds
     * linalg/bidiag        in   5.19 seconds
     * linalg/diagonal      in   6.63 seconds
     * linalg/dense         in   0.00 seconds
     * linalg/pinv          in   4.31 seconds
     * linalg/givens        in   1.79 seconds
     * linalg/cholesky      in   4.83 seconds
     * linalg/lu            in  10.33 seconds
     * linalg/symmetric     in   5.43 seconds
     * linalg/generic       in   0.49 seconds
     * linalg/arnoldi       in   7.73 seconds
     * core                 in  14.43 seconds
     * keywordargs          in   1.46 seconds
     * numbers              in  43.85 seconds
     * printf               in   2.37 seconds
     * char                 in   0.66 seconds
     * string               in  18.89 seconds
     * triplequote          in   0.22 seconds
     * unicode              in  10.65 seconds
     * dates                in  56.57 seconds
     * dict                 in  12.23 seconds
     * hashing              in   5.64 seconds
     * remote               in   0.41 seconds
     * iobuffer             in   1.44 seconds
     * staged               in   0.68 seconds
     * arrayops             in  32.77 seconds
     * tuple                in   1.06 seconds
     * subarray             in 203.71 seconds
     * reduce               in   3.85 seconds
     * reducedim            in  18.60 seconds
     * random               in  12.76 seconds
     * abstractarray        in  29.96 seconds
     * intfuncs             in   0.80 seconds
     * simdloop             in   1.14 seconds
     * blas                 in   3.08 seconds
     * sparse               in  66.65 seconds
     * bitarray             in  67.82 seconds
     * copy                 in   2.00 seconds
     * math                 in  10.78 seconds
     * fastmath             in   4.71 seconds
     * functional           in   1.22 seconds
     * operators            in   0.18 seconds
     * path                 in   3.13 seconds
     * ccall                in   2.17 seconds
     * parse                in   1.60 seconds
     * loading              in   0.08 seconds
     * bigint               in   2.71 seconds
     * sorting              in  30.55 seconds
     * statistics           in   8.23 seconds
     * spawn                      [stdio passthrough ok]
ERROR: syntax: invalid escape sequence
jl_uv_writecb() ERROR: broken pipe EPIPE```

[yuyichao]

Wow, they have a new interface!

The error message is due to #12144 (comment) and the hang is the usual one....

[ScottPJones]

Sorry about that, @malmaud! Somehow I messed up when #11908 got closed, and I had to move the changes to #11925. Part of your change got in correctly, but the part now in strings/util.jl did not.

[yuyichao]

Restarted AppVeyor. Original failure here

[tkelman]

Wow, they have a new interface!

AppVeyor still looks the same to me, are you referring to the tweaked PR status indicator here on github?

[yuyichao]

are you referring to the tweaked PR status indicator here on github?

Yes