rustup update doesn't give the same info as rustup update [toolchain]

Not sure if this is intended or not, but it caused me a bit of confusion for a second.
rustup version: rustup 1.6.0 (a11c01e8c 2017-08-30)

Example rustup udpate:

ayyy@lmao:~$ rustup update
info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'
info: latest update on 2017-08-31, rust version 1.20.0 (f3d6973f4 2017-08-27)
info: downloading component 'rustc'
info: downloading component 'rust-std'
info: downloading component 'cargo'
info: downloading component 'rust-docs'
info: removing component 'rustc'
info: removing component 'rust-std'
info: removing component 'cargo'
info: removing component 'rust-docs'
info: installing component 'rustc'
info: installing component 'rust-std'
info: rolling back changes
error: could not rename component directory from '/home/ayyy/.rustup/tmp/h8hipktpem0zivuh_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/ttg877_3qsc6p19y_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/doc'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/mmybksvd3gf7pnky_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/man'
error: failed to extract package
info: syncing channel updates for 'nightly-x86_64-unknown-linux-gnu'
info: latest update on 2017-09-01, rust version 1.21.0-nightly (97b01abf3 2017-08-31)
info: downloading component 'rustc'
info: downloading component 'rust-std'
info: downloading component 'cargo'
info: downloading component 'rust-docs'
info: downloading component 'rust-src'
info: downloading component 'rust-analysis'
info: downloading component 'rls'
info: removing component 'rustc'
info: removing component 'rust-std'
info: removing component 'cargo'
info: removing component 'rust-docs'
info: removing component 'rust-src'
info: removing component 'rust-analysis'
info: removing component 'rls'
info: installing component 'rustc'
info: rolling back changes
error: could not rename component directory from '/home/ayyy/.rustup/tmp/mjh0dg3_8qsgim9x_dir/bk' to '/home/ayyy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/share'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/ueiv97badjzqhe8l_dir/bk' to '/home/ayyy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/share/doc'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/p_gqet1ewgp_373__dir/bk' to '/home/ayyy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/share/man'
error: could not copy file from '/home/ayyy/.rustup/tmp/bbi39d8llvgw6o7z_dir/rustc/lib/librustc_data_structures-9e9d3520f52f8728.so' to '/home/ayyy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/librustc_data_structures-9e9d3520f52f8728.so'
info: checking for self-updates

   stable-x86_64-unknown-linux-gnu update failed - rustc 1.19.0 (0ade33941 2017-07-17)
  nightly-x86_64-unknown-linux-gnu update failed - rustc 1.21.0-nightly (52a330969 2017-07-27)

example rustup update stable

ayyy@lmao:~$ rustup update stable
info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'
info: latest update on 2017-08-31, rust version 1.20.0 (f3d6973f4 2017-08-27)
info: downloading component 'rustc'
info: downloading component 'rust-std'
info: downloading component 'cargo'
info: downloading component 'rust-docs'
info: removing component 'rustc'
info: removing component 'rust-std'
info: removing component 'cargo'
info: removing component 'rust-docs'
info: installing component 'rustc'
info: installing component 'rust-std'
info: rolling back changes
error: could not rename component directory from '/home/ayyy/.rustup/tmp/i1rrw2ou4pyrq86i_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/yhaswzpceuaea990_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/doc'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/j29s2wtvu7kj3mky_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/man'
error: failed to extract package
info: caused by: failed to unpack `rust-std-1.20.0-x86_64-unknown-linux-gnu/rust-std-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknow` into `/home/ayyy/.rustup/tmp/8rcvfnrtvjg5b7vm_dir/rust-std-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-unknown-linux-gnu/lib/librustc_metadata-13da673fe759b483.so`
info: caused by: No space left on device (os error 28)

It ended up being that I didn't have enough space (only 300MB left), but getting the info on why an error occurred, even if they are different for different toolchains, would still be helpful.
I haven't tested what it says if you only have one toolchain installed, so I'm not completely sure in that situation; #1243 seems to suggest that it still happens, though.

Interesting, i fixed the disk space thing, now im getting a different error, this one specifically about renaming the directories. Not sure what is going on.

ayyy@lmao:~$ rustup update stable
info: syncing channel updates for 'stable-x86_64-unknown-linux-gnu'
214.6 KiB / 214.6 KiB (100 %) 103.5 KiB/s ETA:   0 s                
info: latest update on 2017-08-31, rust version 1.20.0 (f3d6973f4 2017-08-27)
info: downloading component 'rustc'
info: downloading component 'rust-std'
info: downloading component 'cargo'
info: downloading component 'rust-docs'
info: removing component 'rustc'
info: removing component 'rust-std'
info: removing component 'cargo'
info: removing component 'rust-docs'
info: installing component 'rustc'
info: installing component 'rust-std'
info: rolling back changes
error: could not rename component directory from '/home/ayyy/.rustup/tmp/46k0o34x0iug5hy7_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/i28tveossg7_ul2r_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/doc'
error: could not rename component directory from '/home/ayyy/.rustup/tmp/1mgq23blrunnn7wr_dir/bk' to '/home/ayyy/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/share/man'
error: failed to install component: 'rust-std-x86_64-unknown-linux-gnu', detected conflict: '"lib/rustlib/x86_64-unknown-linux-gnu/lib/libstd-29fb1fb52cf57377.rlib"'

edit: removing the conflicting library fixed it, just not sure why it occurred in the first place.

[rbtcollins]

This is another instance of missing/corrupt manifest data. Without knowledge of the installed file, rustup cannot remove it prior to installing the updated version, and then hits a conflict due to the file already existing, and you get the error.

We've got a bunch of these bugs scattered all over the place, I'm closing them all to bring order. See #2417.

The first thing you posted showed the error right before checking for self-updates:

error: could not copy file from '/home/ayyy/.rustup/tmp/bbi39d8llvgw6o7z_dir/rustc/lib/librustc_data_structures-9e9d3520f52f8728.so' to '/home/ayyy/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/librustc_data_structures-9e9d3520f52f8728.so'

And after that you were in trouble - see the bug I've linked for details.