Keep line separators "as is" for an unmodified lines

In our very old and legacy project we have inconsistant line separators in the source files. 

One .cs file can have a line that ends with CRLF and then next line can be ended with LF.

But the Rider changes all line separators to the system dependent (or selected) type on Save.

And this leads to a situation when git commit looks unreadable in SourceTree and console GIT clients.

We need a possibility to select the option in the settings "keep unmodified line separators".

P.S. Visual Studion can do this