Fix insufficient escaping

[GunnarFarneback]

Add another backslash for sufficient escaping. The single backslash is fine in a regex but the regex is embedded within a regular string.

[codecov-io]

Codecov Report

Merging #459 into master will decrease coverage by 3.71%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #459      +/-   ##
==========================================
- Coverage   84.91%   81.19%   -3.72%     
==========================================
  Files           2        2              
  Lines         338      335       -3     
==========================================
- Hits          287      272      -15     
- Misses         51       63      +12     

Impacted Files	Coverage Δ
src/PackageCompiler.jl	81.63% <ø> (-3.01%)	⬇️
src/juliaconfig.jl	76.66% <0.00%> (-10.84%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8d31d60...6143260. Read the comment docs.

[KristofferC]

Oops, thanks.

[NHDaly]

Ah, damn, you beat me to it! 😁

This was exposed by the logging added here: #457

Great fix! (If I might ask: how did you discover this? Do you have some tricks for manually or automatically reviewing the precompile statements generated by PackageCompiler)?

[GunnarFarneback]

I have an embedded application which still has a startup time of 25 seconds with a system image so as a part of looking for low hanging fruit I hacked the logging of "failed to execute" to a println and noticed that the output looked funny (it was in Windows and there "\1" prints as something roughly similar to ⦿).

[NHDaly]

Amazing. thanks for the detailed 👁️ (or ⦿? 😉)