respect the reported number of bytes written

write() is blocking, but apparently may still not write the
entire requested block (for various reasons). It is safest to
NOT assume it wrote everything, and instead check the return
value for the number of bytes actually written.

Author: jamis

lib/mongo/socket.rb

@@ -491,9 +491,8 @@ def write_without_timeout(*args)
         buf = buf.to_s
         i = 0
         while i < buf.length
-          chunk = buf[i...i+WRITE_CHUNK_SIZE]
-          @socket.write(chunk)
-          i += WRITE_CHUNK_SIZE
+          chunk = buf[i, WRITE_CHUNK_SIZE]
+          i += @socket.write(chunk)
         end
       end
     end