Issue 1:
e.g. in https://build.julialang.org/#/builders/79/builds/6315/steps/5/logs/stdio

nested task error: Failed - mbedTLS: ctr_drbg_init returned (-0x0034) CTR_DRBG - The entropy source failed while requesting

Issue 2:
Not sure how to expect this to be handled, but saw it on CI:

Error in testset Downloads:
Error During Test at /Users/julia/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/runtests.jl:184
Got exception outside of a @test
TaskFailedException

nested task error: Failed - mbedTLS: ctr_drbg_init returned (-0x0034) CTR_DRBG - The entropy source failed while requesting https://httpbingo.julialang.org/delay/2?id=37
Stacktrace:
[1] (::Downloads.var"#9#17"{IOBuffer, Base.DevNull, Nothing, Vector{Pair{String, String}}, Nothing, Bool, Bool, String, Int64, Bool, Bool})(easy::Downloads.Curl.Easy)
@ Downloads ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:313
[2] with_handle(f::Downloads.var"#9#17"{IOBuffer, Base.DevNull, Nothing, Vector{Pair{String, String}}, Nothing, Bool, Bool, String, Int64, Bool, Bool}, handle::Downloads.Curl.Easy)
@ Downloads.Curl ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Curl/Curl.jl:43
[3] #8
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:267 [inlined]
[4] arg_write(f::Downloads.var"#8#16"{Base.DevNull, Nothing, Vector{Pair{String, String}}, Nothing, Bool, Bool, String, Int64, Bool, Bool}, arg::IOBuffer)
@ ArgTools ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/ArgTools/src/ArgTools.jl:112
[5] #7
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:266 [inlined]
[6] arg_read
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/ArgTools/src/ArgTools.jl:61 [inlined]
[7] request(url::String; input::Nothing, output::IOBuffer, method::Nothing, headers::Vector{Pair{String, String}}, progress::Nothing, verbose::Bool, throw::Bool, downloader::Downloads.Downloader)
@ Downloads ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:265
[8] #3
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:182 [inlined]
[9] arg_write(f::Downloads.var"#3#4"{Nothing, Vector{Pair{String, String}}, Nothing, Bool, Downloads.Downloader, String}, arg::IOBuffer)
@ ArgTools ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/ArgTools/src/ArgTools.jl:112
[10] #download#2
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Downloads/src/Downloads.jl:181 [inlined]
[11] (::Main.Test99Main_Downloads.var"#2#3"{Base.Iterators.Pairs{Symbol, Downloads.Downloader, Tuple{Symbol}, NamedTuple{(:downloader,), Tuple{Downloads.Downloader}}}, String})(output::IOBuffer)
@ Main.Test99Main_Downloads ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/setup.jl:12
[12] sprint(::Function; context::Nothing, sizehint::Int64)
@ Base ./strings/io.jl:105
[13] sprint
@ ./strings/io.jl:101 [inlined]
[14] #download_body#1
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/setup.jl:11 [inlined]
[15] #download_json#4
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/setup.jl:17 [inlined]
[16] macro expansion
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/runtests.jl:197 [inlined]
[17] (::Main.Test99Main_Downloads.var"#15#29"{Downloads.Downloader, String, Int64})()
@ Main.Test99Main_Downloads ./task.jl:395

...and 37 more exceptions.

Stacktrace:
[1] sync_end(c::Channel{Any})
@ Base ./task.jl:353
[2] macro expansion
@ task.jl:372 [inlined]
[3] macro expansion
@ timing.jl:276 [inlined]
[4] macro expansion
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/runtests.jl:195 [inlined]
[5] macro expansion
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1144 [inlined]
[6] macro expansion
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/runtests.jl:185 [inlined]
[7] macro expansion
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1144 [inlined]
[8] top-level scope
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/stdlib/v1.6/Downloads/test/runtests.jl:4
[9] include
@ ./Base.jl:386 [inlined]
[10] macro expansion
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/test/testdefs.jl:24 [inlined]
[11] macro expansion
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Test/src/Test.jl:1144 [inlined]
[12] macro expansion
@ ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/test/testdefs.jl:23 [inlined]
[13] macro expansion
@ ./timing.jl:353 [inlined]
[14] runtests(name::String, path::String, isolate::Bool; seed::UInt128)
@ Main ~/buildbot/worker-tabularasa/tester_macos64/build/share/julia/test/testdefs.jl:21
[15] (::Distributed.var"#106#108"{Distributed.CallMsg{:call_fetch}})()
@ Distributed ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278
[16] run_work_thunk(thunk::Distributed.var"#106#108"{Distributed.CallMsg{:call_fetch}}, print_error::Bool)
@ Distributed ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:63
[17] macro expansion
@ ~/buildbot/worker/package_macos64/build/usr/share/julia/stdlib/v1.6/Distributed/src/process_messages.jl:278 [inlined]
[18] (::Distributed.var"#105#107"{Distributed.CallMsg{:call_fetch}, Distributed.MsgHeader, Sockets.TCPSocket})()
@ Distributed ./task.jl:395

https://build.julialang.org/#/builders/79/builds/5443