Description of problem:
Opening :Explorer in a new window, after opening certain kinds of files, results
in an annoying error.

Version-Release number of selected component (if applicable):
vim-enhanced-7.0.109-3

How reproducible:
Always. gvim/vim 7

Steps to Reproduce:
1. vim /etc/services
2. Ctrl-W N             # open a new window
3. :E                   # file explorer
  
Actual results:
Error detected while processing function <SNR>14_Highlight_Matching_Pair:
line   17:
E316: ml_get: cannot find line 8

Expected results:

Additional info:
If in step 1) above you instead open /etc/fstab, before doing steps 2 & 3, the
:Explorer opens without error. Also, if after opening the new window you switch
back to the already open file window and do :E, it works.

Disabling syntax highlighting doesn't fix this; not quite sure what's causing
it, but it is does get annoying sometimes.