This is a lesson learned I'd like to share.  tl;dr beware the bash hash.

While running a TurnKey Core guest, I decided to replace vim-tiny with the full version.

# apt-get remove vim-tiny
# apt-get install vim

Upon my next attempt to run vim, bash replied with an error:

# vim
bash: /usr/local/bin/vim: No such file or directory

Bash is still searching for vim-tiny's symbolic link at /usr/local/bin/vim, but I just uninstalled it.  The PATH environment variable is valid, and which sees vim.

# env | grep -i path
PATH=/usr/lib/git-core:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

# which vim
/usr/bin/vim

There is no bash alias for vim, so as a final effort to find some clue I ran:

# type vim
vim is hashed (/usr/local/bin/vim)

According to bash's man page:

Bash uses a hash table to remember the full pathnames of
executable files (see hash under SHELL BUILTIN COMMANDS
below).  A full search of the directories in PATH is
performed only if the command is not found in the hash table.

So because the bash hash remembered the vim-tiny symbolic link, I could not simply run vim from the command line anymore.  The fix is to tell bash hash to either forget about vim, or remember vim's new location.

# hash vim
# vim
success \o/

Hopefully this helps fellow newbs avoid spending too much time trying to figure this out