Remove lock during downloads #630

Job	Run time
test-juliaup (x86_64-pc-windows-msvc)	1m 39s
check-juliaup (x86_64-pc-windows-msvc-windowsstore)	1m 7s
test-juliaup (x86_64-pc-windows-gnu)	1m 34s
check-juliaup (x86_64-pc-windows-msvc-windowsappinstaller)	1m 9s
test-juliaup (x86_64-apple-darwin)	1m 41s
check-juliaup (x86_64-pc-windows-gnu-msi)	1m 8s
test-juliaup (x86_64-unknown-linux-gnu)	1m 33s
check-juliaup (x86_64-pc-windows-gnu-msi)	1m 8s
test-juliaup (x86_64-unknown-linux-musl)	1m 39s
check-juliaup (x86_64-apple-darwin)	1m 6s
test-juliaup (i686-pc-windows-msvc)	1m 39s
check-juliaup (x86_64-unknown-linux-gnu)	1m 10s
test-juliaup (i686-pc-windows-gnu)	1m 36s
check-juliaup (x86_64-unknown-linux-musl)	2m 52s
check-juliaup (i686-pc-windows-msvc-windowsstore)	1m 10s
check-juliaup (i686-pc-windows-msvc-windowsappinstaller)	1m 10s
check-juliaup (i686-pc-windows-gnu-msi)	1m 7s
check-juliaup (i686-unknown-linux-gnu)	1m 12s
check-juliaup (i686-unknown-linux-musl)	1m 10s
check-juliaup (aarch64-unknown-linux-gnu)	2m 52s
check-juliaup (aarch64-unknown-linux-musl)	1m 12s
check-juliaup (aarch64-apple-darwin)	1m 13s
	32m 7s

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