[PATCH 0 of 2] Fix incorrect output when renaming largefiles (issue3093)

[Na'Tosha Bard]

This case actually turned out not to be an issue with renaming itself, but to be an issue with a messy dirstate causing very confusing status output after running 'hg rename' (or 'hg copy', for that matter) on a largefile.  If the user comitted a rename (or copy), despite the confusing output of status, expected behavior occured.  This patch fixes the messy dirstate so that the output of 'hg status' is correct.  It also introduces test cases to prevent regressions.  A separate issue regarding the fact that names for any files containing the default shortname could be mangled during a copy or rename is fixed in a separate patch.