Running tests outside of test/ broken since #8745

[tkelman]

#8745 removed a cd() do in test/runtests.jl that was actually necessary for running the tests from outside of the test directory (e.g. for Base.runtests). #12212 fixes it for JULIA_CPU_CORES=1, but not the parallel case:

tkelman@ygdesk:~/Julia/julia$ ./julia -e 'Base.runtests("all", 2)'
exception on 1: ERROR: SystemError: opening file /home/tkelman/Julia/julia/testdefs.jl: No such file or directory
 in open at ./iostream.jl:90
 in open at ./iostream.jl:112
 in readall at io.jl:250
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
exception on 1: ERROR: SystemError: opening file /home/tkelman/Julia/julia/testdefs.jl: No such file or directory
 in open at ./iostream.jl:90
 in open at ./iostream.jl:112
 in readall at io.jl:250
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
exception on 2: exception on 3: ERROR: MethodError: `include_string` has no method matching include_string(::SystemError, ::ASCIIString)
Closest candidates are:
  include_string(!Matched::Union{UTF8String,ASCIIString}, ::Union{UTF8String,ASCIIString})
  include_string(!Matched::AbstractString, ::AbstractString)
 in include_from_node1 at ./loading.jl:200
 in eval at sysimg.jl:14
 in anonymous at multi.jl:1321
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
ERROR: MethodError: `include_string` has no method matching include_string(::SystemError, ::ASCIIString)
Closest candidates are:
  include_string(!Matched::Union{UTF8String,ASCIIString}, ::Union{UTF8String,ASCIIString})
  include_string(!Matched::AbstractString, ::AbstractString)
 in include_from_node1 at ./loading.jl:200
 in eval at sysimg.jl:14
 in anonymous at multi.jl:1321
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
exception on exception on 2: 3: ERROR: UndefVarError: runtests not defined
 in anonymous at /home/tkelman/Julia/julia/usr/share/julia/test/runtests.jl:14
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
ERROR: UndefVarError: runtests not defined
 in anonymous at /home/tkelman/Julia/julia/usr/share/julia/test/runtests.jl:14
 in anonymous at multi.jl:822
 in run_work_thunk at multi.jl:584
 in anonymous at task.jl:822
ERROR: LoadError: UndefVarError: runtests not defined
 in anonymous at task.jl:1394
while loading /home/tkelman/Julia/julia/usr/share/julia/test/runtests.jl, in expression starting on line 5
ERROR: A test has failed. Please submit a bug report (https://github.com/JuliaLang/julia/issues)
including error messages above and the output of versioninfo():
Julia Version 0.4.0-dev+6138
Commit 50a1068* (2015-07-21 02:58 UTC)
Platform Info:
  System: Linux (x86_64-linux-gnu)
  CPU: Intel(R) Core(TM)2 Duo CPU     E8400  @ 3.00GHz
  WORD_SIZE: 64
  BLAS: libopenblas (USE64BITINT DYNAMIC_ARCH NO_AFFINITY Penryn)
  LAPACK: libopenblas
  LIBM: libopenlibm
  LLVM: libLLVM-3.3

 in error at ./error.jl:21
 in runtests at interactiveutil.jl:406
 in process_options at ./client.jl:284
 in _start at ./client.jl:411

Not sure whether there's any better fix than putting the cd back.