Self-update in parallel processes does not work properly

[alexey-igrychev]

Currently, the library does not resolve possible conflicts when performing a self-update in parallel processes (and probably should not). The user might face the following errors:

# unix: attempt to update current program path that points to non-existent file after the parallel self-update
Error: rename /home/user/go/bin/.binary.old /home/user/go/bin/..binary.old.old: no such file or directory

# windows: attempt to replace the real current binary file (.binary.exe.old) with the result binary file (binary.exe) from the parallel self-update
Error: rename C:\Users\user\go\bin\binary.exe C:\Users\user\go\bin\.binary.exe.old: Access is denied.

To avoid such issues, locking together with a delay between updates can be used (example here).