drop_exists() is case-sensitive

[dholstius]

drop_exists() is case-sensitive. This means that it will incorrectly return FALSE in the following scenario:

1. Alice creates (in her Dropbox) a file named /Foo/bar/baz.txt.
2. Alice shares /Foo/ with Bob.
3. Bob renames (on his filesystem) the subfolder bar/ to Bar/.
4. Bob invokes drop_exists("/Foo/Bar/baz.txt"), expecting the result to be TRUE.

Following up with a pull request.

[J-Moravec]

Wouldn't case insensitive mean that the following scenario will be incorrect?

On a case-sensitive system (i.e., Linux):

1. Alice creates in her Dropbox) a file named /Foo/bar/baz.txt
2. Bob checks if /Foo/bar/BAZ.txt exists. After your fix, the return will be TRUE.
3. Bob tries to read /Foo/Bar/BAZ.txt using R (such as with readLines().
4. Operation fails, Bob is bamboozled.