[release/1.0] archive: fix logic for skipping mknod when running in userns

[AkihiroSuda]

Signed-off-by: Akihiro Suda suda.akihiro@lab.ntt.co.jp

cherry-pick #2163

[codecov-io]

Codecov Report

Merging #2179 into release/1.0 will increase coverage by 0.01%.
The diff coverage is 50%.

@@               Coverage Diff               @@
##           release/1.0    #2179      +/-   ##
===============================================
+ Coverage        50.56%   50.57%   +0.01%     
===============================================
  Files               81       81              
  Lines             7169     7171       +2     
===============================================
+ Hits              3625     3627       +2     
  Misses            2849     2849              
  Partials           695      695

Flag	Coverage Δ
#linux	50.57% <50%> (+0.01%)	⬆️

Impacted Files	Coverage Δ
archive/tar_unix.go	52.38% <50%> (+1.56%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update cfd0439...a3372da. Read the comment docs.

[estesp]

LGTM

[crosbymichael]

LGTM