Wrong default REPL prompt when `JULIA_DEPOT_PATH` is a symlink

[christiangnrd]

Found when trying to run tests on master but this happens all the way back to at least 1.5.

Discovered because of new tests.

Test Failed at /Users/christian/.julia/juliaup/julia-nightly/share/julia/stdlib/v1.12/REPL/test/repl.jl:1971
  Expression: prompt == "(@v$(VERSION.major).$(VERSION.minor)) pkg> "
   Evaluated: "(v1.12) pkg> " == "(@v1.12) pkg> "

Seems like projname(project_file::String) only checks abspath instead of safe_realpath when comparing envdir and project_file

julia/stdlib/REPL/src/Pkg_beforeload.jl

Lines 89 to 94 in fc9f147

	for depot in Base.DEPOT_PATH
	envdir = joinpath(depot, "environments")
	if startswith(abspath(project_file), abspath(envdir))
	return "@" * name
	end
	end

Repl walkthrough of my investigation:

               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.12.0-DEV.1238 (2024-09-23)
 _/ |\__'_|_|_|\__'_|  |  Commit 0fade450a18 (0 days old master)
|__/                   |

julia> withenv("JULIA_DEPOT_PATH" => mktempdir(), "JULIA_LOAD_PATH" => nothing) do
              run(`$(Base.julia_cmd()[1]) --startup-file=no`)
          end
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.12.0-DEV.1238 (2024-09-23)
 _/ |\__'_|_|_|\__'_|  |  Commit 0fade450a18 (0 days old master)
|__/                   |

julia> using REPL; REPL.Pkg_promptf()
[ Info: Precompiling REPL [3fa0cd96-eef1-5676-8a61-b3b8758bbffb] 
"(v1.12) pkg> "

julia> depot = Base.DEPOT_PATH |> first
"/var/folders/4g/lnkpkf3s4rxd_wbl8vwnqs4r0000gn/T/jl_KEaptd"

julia> envdir = joinpath(depot, "environments")
"/var/folders/4g/lnkpkf3s4rxd_wbl8vwnqs4r0000gn/T/jl_KEaptd/environments"

julia> project_file = REPL.find_project_file()
"/private/var/folders/4g/lnkpkf3s4rxd_wbl8vwnqs4r0000gn/T/jl_KEaptd/environments/v1.12/Project.toml"

julia> startswith(abspath(project_file), abspath(envdir)) # Line 91 in Pkg_beforeload.jl
false