Allow customizing the kernel display name

This adds a `installkernel(; displayname)` argument to let the user specify the
kernel display name completely.

deps/kspec.jl

@@ -54,10 +54,16 @@ else
     exe(s::AbstractString, e::AbstractString) = s * e
 end
 
+function display_name(name::AbstractString)
+    debugdesc = ccall(:jl_is_debugbuild,Cint,())==1 ? "-debug" : ""
+    return name * " " * Base.VERSION_STRING * debugdesc
+end
+
 """
     installkernel(name::AbstractString, options::AbstractString...;
                   julia::Cmd,
                   specname::AbstractString,
+                  displayname::AbstractString,
                   env=Dict())
 
 Install a new Julia kernel, where the given `options` are passed to the `julia`
@@ -71,6 +77,9 @@ kernelpath = installkernel("Julia O3", "-O3", env=Dict("FOO"=>"yes"))
 creates a new Julia kernel in which `julia` is launched with the `-O3`
 optimization flag and `FOO=yes` is included in the environment variables.
 
+The `displayname` argument can be used to customize the name displayed in the
+Jupyter kernel list.
+
 The returned `kernelpath` is the path of the installed kernel directory,
 something like `/...somepath.../kernels/julia-o3-1.6` (in Julia 1.6).  The
 `specname` argument can be passed to alter the name of this directory (which
@@ -96,6 +105,7 @@ installkernel(
 function installkernel(name::AbstractString, julia_options::AbstractString...;
                    julia::Cmd = `$(joinpath(Sys.BINDIR,exe("julia")))`,
                    specname::AbstractString = kernelspec_name(name),
+                   displayname::AbstractString = display_name(name),
                    env::Dict{<:AbstractString}=Dict{String,Any}())
     # Is IJulia being built from a debug build? If so, add "debug" to the description.
     debugdesc = ccall(:jl_is_debugbuild,Cint,())==1 ? "-debug" : ""
@@ -112,7 +122,7 @@ function installkernel(name::AbstractString, julia_options::AbstractString...;
 
         ks = Dict(
             "argv" => kernelcmd_array,
-            "display_name" => name * " " * Base.VERSION_STRING * debugdesc,
+            "display_name" => displayname,
             "language" => "julia",
             "env" => env,
             # Jupyter's signal interrupt mode is not supported on Windows

test/install.jl

@@ -22,9 +22,13 @@ import IJulia, JSON
         end
     end
 
-    let kspec = IJulia.installkernel("ahzAHZ019.-_ ~!@#%^&*()")
+    let kspec = IJulia.installkernel("ahzAHZ019.-_ ~!@#%^&*()"; displayname="foo")
         try
             @test occursin("ahzahz019.-_-__________", basename(kspec))
+
+            let k = open(JSON.parse, joinpath(kspec, "kernel.json"))
+                @test k["display_name"] == "foo"
+            end
         finally
             rm(kspec, force=true, recursive=true)
         end