git (git-gui): prevent wish from interpreting git-gui options

While the /cmd/git-gui.exe wrapper was never intended to be used
directly via the command-line (`git-gui` is the long-deprecated dashed
form, after all), it *should* ideally be possible to pass command-line
parameters to that wrapper.

One reported problem was that wish.exe thinks that the options starting
with a dash are intended for its use. What we need to do is simply
separate the git-gui options from the (non-existing) wish options using
a double dash.

This fixes git-for-windows/git#1284

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

mingw-w64-git/git-wrapper.c

@@ -539,6 +539,7 @@ int main(void)
 		}
 		is_git_command = 0;
 		PathAppend(buffer, L"git-gui");
+		wcsncat(buffer, L" --", BUFSIZE - wcslen(buffer) - 1);
 		prefix_args = buffer;
 		prefix_args_len = wcslen(buffer);
 	}