Language server update fails if another window is open (Linux)

[Amanieu]

The following error occurs when updating the language server while another VSCode window is open:

[2020-04-08 16:24:02.327] [exthost] [error] Activating extension matklad.rust-analyzer failed due to an error:
[2020-04-08 16:24:02.327] [exthost] [error] Error: ETXTBSY: text file is busy, open '/home/amanieu/.config/Code/User/globalStorage/matklad.rust-analyzer/rust-analyzer-linux'

Linux won't let you write to an executable file directly if it is in use since this will truncate the existing file to 0 and cause the process to crash. Instead you should download to a separate file name and then rename it to rust-analyzer-linux once the download is complete.

[lnicola]

See also #3403. Unfortunately, the delete and rename trick doesn't work on Windows.