I am trying to commit using :Gcommit. A split window appears. I think I am supposed to enter the commit message there. However, when I press "i" to enter the insert mode, the buffer changes and I see lines, which are looking like the follwing one.
100644 f4ae5fb126cf3316410e05d113802464791b3813 0 filename
When I press "i" again, I am back to the window where I would like to enter the commit message.
Question: How do I enter the insert mode in this situation in order to enter the commit message?
(I am using vim-fugitive commit d854197c03c0b027cca41abf86a5557c5473b82f.)