Arch Linux

Description:
When executing vim <filename> after vim opens the file a 'g' (lowercase g) is automatically inserted into the file at the last remembered cursor position.
By pressing 'u' for undo the change goes away.

Downgrading vim and vim-runtime to 7.4.738-1 fixes the problem.
Bug reproducable with vim and vim-runtime 7.4.764-1 and 7.4.778-1

Since there is a dependency between vim and vim-runtime I could not find out which of the 2 packages brings the problem.

Does not happen with vi (--> ex)

Additional info:
* package version(s)
buggy
vim-7.4.764-1-x86_64.pkg.tar.xz
vim-runtime-7.4.764-1-x86_64.pkg.tar.xz
vim-7.4.778-1-x86_64.pkg.tar.xz
vim-runtime-7.4.778-1-x86_64.pkg.tar.xz

working
vim-7.4.738-1-x86_64.pkg.tar.xz
vim-runtime-7.4.738-1-x86_64.pkg.tar.xz

* config and/or log files etc.

#/etc/vimrc
runtime! archlinux.vim

#/usr/share/vim/vimfiles/archlinux.vim
set nocompatible " Use Vim defaults instead of 100% vi compatibility
set backspace=indent,eol,start " more powerful backspacing
set history=50 " keep 50 lines of command line history
set ruler " show the cursor position all the time
set suffixes=.bak,~,.swp,.o,.info,.aux,.log,.dvi,.bbl,.blg,.brf,.cb,.ind,.idx,.ilg,.inx,.out,.toc,.png,.jpg

if has('gui_running')
" Make shift-insert work like in Xterm
map <S-Insert> <MiddleMouse>
map! <S-Insert> <MiddleMouse>
endif

# no .vimrc in ~/
# no .viminfo in ~/
# no .vim* in ~/

Steps to reproduce:

Install vim and vim-runtime version 7.4.778-1-x86_64, create a new file by executing vim <filename> and enter

#!/bin/bash

as first line. Store the file with :wq

Reopen the file with vim <filename>

The '#' will become a 'g'.

Pressing 'u' will undo and change the 'g' back to a '#'.