Render Slow Motion File using Source Mark in to Out usually doesn't render correct location

What steps will reproduce the problem?

1. add video file (mine was MPEG4.avi)
2. using clip monitor Mark In and Out points to create slowmo clip location
3. select Render Slow/Fast motion file using Render Range source Mark In to 
Source Mark Out and a setting other than 100% target speed (say 50%)

What is the expected output? What do you see instead?

I expected the clip within the In Out Range to be slowed at the correct speed. 
Instead, a seemingly random location on the Source Strip was selected and 
slowed accordingly. 

What version of the product are you using? On what operating system?

Flowblade 0.8 on Linux Mint Nadia 14.

More Info

Only choosing to render a clip at 100% speed default results in the correct 
location being rendered every time. Rarely, it seemed to work correctly, 
though.

Original issue reported on code.google.com by pepis...@googlemail.com on 28 Apr 2013 at 4:20

gcarranza / flowblade

Render Slow Motion File using Source Mark in to Out usually doesn't render correct location #36