Iterators: always initialize cur_index_ with 0.

9 jobs for mh_optimization in 3 minutes and 39 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Test
passed clang-c++11 #133377
Linux

00:03:38

passed cppcheck #133379
Linux

00:00:30

passed doc #133384
Linux

00:00:07

passed gcc-c++11 #133376
Linux

00:03:11

passed macos-c++11 #133378
Apple

00:02:08

passed VS2015-32-bit #133383
VS2015

00:01:19

passed VS2015-64-bit #133382
VS2015

00:01:33

passed VS2017-32-bit #133381
VS2017

00:01:20

passed VS2017-64-bit #133380
VS2015

00:01:36