patch 7.4.894
Problem:    vimrun.exe is picky about the number of spaces before -s.
Solution:   Skip all spaces. (Cam Sinclair)
diff --git a/src/vimrun.c b/src/vimrun.c
index c423e6c..0006479 100644
--- a/src/vimrun.c
+++ b/src/vimrun.c
@@ -79,6 +79,8 @@
 	}
 	++p;
     }
+    while (*p == ' ')
+        ++p;
 
     /*
      * "-s" argument: don't wait for a key hit.