precompile loads the wrong library after recompile_stale

[vtjnash]

the return value of compilecache is being ignored by recompile_stale, leading to state corruption and loading of the wrong file:

juser@juliabox:~$ /opt/julia-0.4.6/bin/julia                                                                                                                           
               _
   _       _ _(_)_     |  A fresh approach to technical computing                                                                                                      
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org                                                                                                     
   _ _   _| |_  __ _   |  Type "?help" for help.                                                                                                                       
  | | | | | | |/ _` |  |                                                                                                                                               
  | | |_| | | | (_| |  |  Version 0.4.6 (2016-06-19 17:16 UTC)                                                                                                         
 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release                                                                                                       
|__/                   |  x86_64-unknown-linux-gnu                                                                                                                     

julia> using JSON                                                                                                                                                      
INFO: Recompiling stale cache file /opt/julia_packages/.julia/lib/v0.4/JSON.ji for module JSON.                                                                        

julia> Base.module_uuid(JSON)                                                                                                                                          
0x0000000000096afb                                                                                                                                                     

julia>                                                                                                                                                                 
juser@juliabox:~$ /opt/julia-0.4.6/bin/julia                                                                                                                           
               _
   _       _ _(_)_     |  A fresh approach to technical computing                                                                                                      
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org                                                                                                     
   _ _   _| |_  __ _   |  Type "?help" for help.                                                                                                                       
  | | | | | | |/ _` |  |                                                                                                                                               
  | | |_| | | | (_| |  |  Version 0.4.6 (2016-06-19 17:16 UTC)                                                                                                         
 _/ |\__'_|_|_|\__'_|  |  Official http://julialang.org/ release                                                                                                       
|__/                   |  x86_64-unknown-linux-gnu                                                                                                                     

julia> using JSON                                                                                                                                                      

julia> Base.module_uuid(JSON)                                                                                                                                          
0x000000001644d120                                                                                                                                                     

[JeffBezanson]

How did you trigger this? The uuids match for me. Or is it 0.4 only?

[ViralBShah]

It is easily triggered on JuliaBox for 0.4.6 when trying to use pyplot as a new user.

[vtjnash]

Yes, tested this from JuliaBox and see the issue. I think I'll do the minimal fix for 0.4 and work on a more comprehensive fix for 0.5. Apparently I need to dog-food the non-trivial precompile states more often.

[ViralBShah]

The JuliaBox.com migration is also blocked on this, which we are trying to do this weekend.

[ViralBShah]

Cc @tanmaykm @nkottary

[ViralBShah]

Is this a 0.5 blocker?