By default, go's tar archiver uses USTAR header format. Unfortunately, this
format doesn't support sub-second resolution for ModTime. Go solves this by
*rounding* the time. Sometimes, this creates an archive containing a file
with modtime from the future. When such archive is untarred by GNU tar,
the following message is produced:
tar: bf548dfd-0a90-40e6-bbf2-dcdd82fcbb4e.json: time stamp 2020-07-13
13:34:31 is 0.356223173 s in the future
We have two options here:
1) Use gnu header format that supports sub-second resolution. Unfortunately,
it seems that not all tar archivers support this format (e.g. 7-zip).
2) The other option is to truncate the date (instead of rounding).
I went with option 2.
Also, this commit adds a test to check that the header is not from the future.
Without this fix, the test is actually failing, I verified this manually.
Fixes#854
454e471af8