export manifest from tar file

[hhstu]

Fixes #1032

[codecov-commenter]

Codecov Report

Merging #1046 (3f91e77) into main (6118d45) will decrease coverage by 0.03%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##             main    #1046      +/-   ##
==========================================
- Coverage   75.15%   75.11%   -0.04%     
==========================================
  Files         107      107              
  Lines        5071     5079       +8     
==========================================
+ Hits         3811     3815       +4     
- Misses        717      719       +2     
- Partials      543      545       +2     

Impacted Files	Coverage Δ
pkg/v1/tarball/image.go	76.82% <50.00%> (-1.38%)	⬇️

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