When constructing the path to the original .frm file ALTER .. RENAME
 was unnecessary (and incorrectly) lowercasing the whole path when not 
 on a case-insensitive filesystem.
 This path should not be modified because of lower_case_table_names
 as it is already in the correct case according to that setting.
 Fixed by removing the lowercasing.
 Unfortunately testing this would require running the tests on a case
 sensitive filesystem in a directory that has uppercase letters.
 This cannot be guaranteed in all setups so no test case added.


sql/sql_table.cc:
  Bug #28754: don't downcase the .frm path