Revert "Enable color output whenever stdout is TTY (#34347)"

[maleadt]

Looks like #34347 broke PkgEval which tests packages using docker without a TTY:

tim@taurus ~/.cache/julia/binaries/nightly/x64$ docker run -it -v $(pwd):/opt/julia tutum/curl /opt/julia/julia -e 'using Pkg; Pkg.add("Example"); Pkg.test("Example")'                                                                                                       
    Cloning default registries into `~/.julia`
######################################################################## 100.0%
      Added registry `General` to `~/.julia/registries/General`
  Resolving package versions...
  Installed Example ─ v0.5.3
   Updating `~/.julia/environments/v1.5/Project.toml`
   7876af07 + Example v0.5.3
   Updating `~/.julia/environments/v1.5/Manifest.toml`
   7876af07 + Example v0.5.3
    Testing Example
     Status `~/tmp/jl_ULb6Wh/Project.toml`
   7876af07 Example v0.5.3
   8dfed614 Test
     Status `~/tmp/jl_ULb6Wh/Manifest.toml`
   7876af07 Example v0.5.3
   2a0f44e3 Base64
   8ba89e20 Distributed
   b77e0a4c InteractiveUtils
   56ddb016 Logging
   d6f4376e Markdown
   9a3f8284 Random
   9e88b42a Serialization
   6462fe0b Sockets
   8dfed614 Test
    Testing Example tests passed 

tim@taurus ~/.cache/julia/binaries/nightly/x64$ docker run -i -v $(pwd):/opt/julia tutum/curl /opt/julia/julia -e 'using Pkg; Pkg.add("Example"); Pkg.test("Example")'                                                                                                        
    Cloning default registries into `~/.julia`
######################################################################## 100.0%
      Added registry `General` to `~/.julia/registries/General`
  Resolving package versions...
  Installed Example ─ v0.5.3
   Updating `~/.julia/environments/v1.5/Project.toml`
   7876af07 + Example v0.5.3
   Updating `~/.julia/environments/v1.5/Manifest.toml`
   7876af07 + Example v0.5.3
    Testing Example
     Status `~/tmp/jl_QRq41T/Project.toml`
   7876af07 Example v0.5.3
   8dfed614 Test
     Status `~/tmp/jl_QRq41T/Manifest.toml`
   7876af07 Example v0.5.3
   2a0f44e3 Base64
   8ba89e20 Distributed
   b77e0a4c InteractiveUtils
   56ddb016 Logging
   d6f4376e Markdown
   9a3f8284 Random
   9e88b42a Serialization
   6462fe0b Sockets
   8dfed614 Test
ERROR: Package Example errored during testing
Stacktrace:
 [1] pkgerror(::String, ::Vararg{String,N} where N) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/Types.jl:53
 [2] test(::Pkg.Types.Context, ::Array{Pkg.Types.PackageSpec,1}; coverage::Bool, julia_args::Cmd, test_args::Cmd, test_fn::Nothing) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/Operations.jl:1523
 [3] test(::Pkg.Types.Context, ::Array{Pkg.Types.PackageSpec,1}; coverage::Bool, test_fn::Nothing, julia_args::Cmd, test_args::Cmd, kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:316
 [4] test(::Pkg.Types.Context, ::Array{Pkg.Types.PackageSpec,1}) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:303
 [5] #test#68 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:297 [inlined]
 [6] test at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:297 [inlined]
 [7] #test#67 at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:296 [inlined]
 [8] test at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:296 [inlined]
 [9] test(::String; kwargs::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:295
 [10] test(::String) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/Pkg/src/API.jl:295
 [11] top-level scope at none:1

As a result the daily PkgEval is broken: https://github.com/JuliaCI/NanosoldierReports/blob/master/pkgeval/by_date/2020-03/27/report.md

Adding --color=no fixes that:

tim@taurus ~/.cache/julia/binaries/nightly/x64$ docker run -i -v $(pwd):/opt/julia tutum/curl /opt/julia/julia --color=no -e 'using Pkg; Pkg.add("Example"); Pkg.test("Example")'                                                                                             
    Cloning default registries into `~/.julia`
######################################################################## 100.0%
      Added registry `General` to `~/.julia/registries/General`
  Resolving package versions...
  Installed Example ─ v0.5.3
   Updating `~/.julia/environments/v1.5/Project.toml`
   7876af07 + Example v0.5.3
   Updating `~/.julia/environments/v1.5/Manifest.toml`
   7876af07 + Example v0.5.3
    Testing Example
     Status `~/tmp/jl_QkNsGT/Project.toml`
   7876af07 Example v0.5.3
   8dfed614 Test
     Status `~/tmp/jl_QkNsGT/Manifest.toml`
   7876af07 Example v0.5.3
   2a0f44e3 Base64
   8ba89e20 Distributed
   b77e0a4c InteractiveUtils
   56ddb016 Logging
   d6f4376e Markdown
   9a3f8284 Random
   9e88b42a Serialization
   6462fe0b Sockets
   8dfed614 Test
    Testing Example tests passed

Opening a PR to run PkgEval and confirm.
@karan0299 could you have a look at why your changes cause this?

[maleadt]

@nanosoldier runtests(["Example"], vs = ":master")

[nanosoldier]

Your package evaluation job has completed - no new issues were detected. A full report can be found here. cc @maleadt

[StefanKarpinski]

Given the multiple issues, we should perhaps actually merge this revert.

[JeffBezanson]

This seems to be because Pkg (as well as several other packages) uses this idiom:

        --color=$(Base.have_color ? "yes" : "no")

when spawning another julia process. This is very unfortunate. This is also supposed to be exactly what julia_cmd() is for. I see it is missing a couple flags, so I'll add them. I would also recommend exporting julia_cmd to encourage using that (not that it will help much, since most cases seem to use both julia_cmd and rolling their own option forwarding).

[KristofferC]

I updated Pkg to be compatible with this change (JuliaLang/Pkg.jl#1746). But maybe it should just wait for #35324?