According to the shebang documentation, it will only consider
the path of the executable, along with the arguments as the consecutive portion after the space that separates
them. Argument splitting would then have to be done elsewhere, probably in the kernel.
To make that work without the kernel, we perform the splitting while Git just ignores options.
For now it seems more compatible to not ignore options, but if it is important this could be changed.
The remainder of the line past the space after interpreter, without leading or trailing whitespace,
as pre-split arguments just like a shell would do it.
Note that we accept that illformed UTF-8 will prevent argument splitting.