Fix FVA in summary calls

[pstjohn]

We've got bigger issues, #520, but this fixes a bug with the FVA handling in summary.

[codecov-io]

Codecov Report

Merging #525 into devel will increase coverage by <.01%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##            devel     #525      +/-   ##
==========================================
+ Coverage   69.43%   69.43%   +<.01%     
==========================================
  Files          64       64              
  Lines        8476     8477       +1     
  Branches     1447     1447              
==========================================
+ Hits         5885     5886       +1     
  Misses       2334     2334              
  Partials      257      257

Impacted Files	Coverage Δ
cobra/flux_analysis/summary.py	80.64% <25%> (+0.21%)	⬆️

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[pstjohn]

yeah I should probably write tests for these... lets see what happens in #520

[hredestig]

cheers for the intermediate improvement!