prevent precompilation from breaking if Base.PkgId is imported (#42329)

`repr` will only print a module prefix if the symbol is not existing in Main but the module prefix is unconditionally needed here since the code will be evaluated in another process.

Author: KristofferC

base/loading.jl

@@ -1356,8 +1356,8 @@ function create_expr_cache(pkg::PkgId, input::String, output::String, concrete_d
     for (pkg, build_id) in concrete_deps
         push!(deps_strs, "$(pkg_str(pkg)) => $(repr(build_id))")
     end
-    deps = repr(eltype(concrete_deps)) * "[" * join(deps_strs, ",") * "]"
-
+    deps_eltype = sprint(show, eltype(concrete_deps); context = :module=>nothing)
+    deps = deps_eltype * "[" * join(deps_strs, ",") * "]"
     trace = isassigned(PRECOMPILE_TRACE_COMPILE) ? `--trace-compile=$(PRECOMPILE_TRACE_COMPILE[])` : ``
     io = open(pipeline(`$(julia_cmd()::Cmd) -O0
                        --output-ji $output --output-incremental=yes