Fix the condition check with the pre-install in generic installer

[LinuxSuRen]

No description provided.

[codecov]

Codecov Report

Merging #255 (4f765ff) into master (70e6a51) will decrease coverage by 0.09%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #255      +/-   ##
==========================================
- Coverage   26.35%   26.25%   -0.10%     
==========================================
  Files          28       28              
  Lines        1878     1885       +7     
==========================================
  Hits          495      495              
- Misses       1358     1365       +7     
  Partials       25       25              

Flag	Coverage Δ
unittests	26.25% <0.00%> (-0.10%)	⬇️

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Impacted Files	Coverage Δ
pkg/os/generic_installer.go	15.27% <0.00%> (-1.65%)	⬇️

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