Bug: Case-insensitive filesystems can cause merge and checkout problems

By default, git sets core.ignorecase=true when git init or git clone is run on a machine with a case-insensitive filesystem. Here's a test-case for some problems that this causes:

git checkout master touch TestCase git add TestCase git commit -m 'add TestCase' git checkout -b with-camel touch foo git add foo git commit -m 'intervening commit' git checkout master git rm TestCase touch testcase git add testcase git commit -m 'rename to testcase' git checkout with-camel git merge master -m 'merge'

One would expect a clean working copy at this point, but in fact, the file 'testcase' will be deleted.

With core.ignorecase=false, we get a different failure.  The
penultimate command fails with:
$ git checkout with-camel
error: The following untracked working tree files would be overwritten
by checkout:
        TestCase
Please move or remove them before you can switch branches.
Aborting

Of course, there is no untracked working tree file by that name; there is a tracked working tree file named testcase (all-lowercase).