Re: Bizarre missing changes (git bug?)

On Mon, 21 Jul 2008, Tim Harper wrote:

Anyone run into this before?  Any idea what might have caused it?  We're a bit
concerned about this because if we don't know how to avoid this, we no longer
can feel certain that when something is committed, it will make it out in our
release.

Read up on '--full-history'.

By default, git simplifies the history for logs that have path 
simplification: only walking down the side of a merge that all the data 
came from (ie the unchanged side). So it only leaves merges around if 
there was changes from _all_ parents.

So without --full-history, if any parent matches the state, it just 
removes the merge and picks that parent that contained all the state. 
Obviously, any changes to that file can be sufficiently explained by 
walking just that limited history, because they must have changed in 
_that_ history too!

That default behaviour leads to a *much* simpler history, and is usually 
what you want - it avoids unnecessary duplication when something was 
changed trivially the same way in both branches - 'git log' will just pick 
the first branch.

So, if you had two (or more) commits that both fixed the same bug in 
different branches, and thus both branches actually ended up with the same 
contents, it does mean that "git log <filename>" will only show _one_ of 
the fixes.

In this case, it apparently showed another version than the one you were 
looking for.

				Linus