Why does my render have a gamma value different from the viewport? Blender seems to be changing the movie clip gamma after rendering. What causes it and how can I fix it?

View Port:


Render:


Here is my .blend file (including 10 frames of the clip).
I opened your file, made a render, too much exposure.
I went to the compositor, turned on the  "backdrop" functions, everything went OK, even the animation rendering!

Looks like a little bug.