tests: avoid case-folding issue in test-evolve-inmemory.t on windows When using debugdrawdag, each commit already creates a file with the same name as the commit description, i.e. changeset C creates file C with 'C' in it (no newline). Creating another file called c breaks this test on windows. So let's reuse the files already created by debugdrawdag. hg update reports one less file because now there's only C in C (yes, I also wanted to change commit descriptions, file names and their contents to be less ambiguous, but decided to be lazy).