Binary files in a linear repository

Hello all,

currently I'm planning a frontend tool which makes use of only a  
small subset of git. The repo's contents is all binary (think of  
pictures). Accordingly, I can't merge in a meaningful way, making  
branches of very limited use.

The situation I'm trying to solve is:

- A revision earlier than the latest one is checked out.

- Files of this earlier commit are modified.

- I want to record this earlier commit along with it's modifications  
as a new commit on top of master, ignoring intermediate commits:

com005  <-- master
com004
com003  <-- HEAD, files modified
com002
com001 (initial commit)

One solution to do this is to move all files somewhere else, check  
out master, deleting all checked out files, placing the moved away  
files back into place and committing the result as com006. Obviously,  
this is a pretty complex operation, just waiting to exploit coding  
mistakes. Additionally, this will be slow.

Now I'm thinking about a much simpler solution: Simply declare the  
current set of files as (a modified) master/com005 and commit them. A  
"cp $GIT_DIR/master $GIT_DIR/HEAD" followed by a commit would do it.

Now my question: Is it safe to tweak the files in $GIT_DIR this way  
or will this corrupt the repository?


Thanks for any opinions,
Markus