[BUG] Cant make forecasting with pipelines, data with nans, and Imputers #466

[martins0n]

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closes #466

[codecov-commenter]

Codecov Report

Merging #473 (f45b682) into master (0ed9c58) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #473      +/-   ##
==========================================
+ Coverage   87.81%   87.83%   +0.01%     
==========================================
  Files         115      115              
  Lines        5450     5450              
==========================================
+ Hits         4786     4787       +1     
+ Misses        664      663       -1     

Impacted Files	Coverage Δ
etna/datasets/tsdataset.py	89.49% <100.00%> (+0.33%)	⬆️

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[iKintosh]

This seems like a temporal solution.
In the future there will be only two ending checks.

1. In the init with a warning.
2. At the end of a make_future method which will result in error if endings are inconsistent. This will ensure that all models work with the data equally.

[martins0n]

This seems like a temporal solution. In the future there will be only two ending checks.

1. In the init with a warning.
2. At the end of a make_future method which will result in error if endings are inconsistent. This will ensure that all models work with the data equally.

Could you create issue, please?