rebase: use "rebase.collapse" as "editform" for "--collapse" always Before this patch, if both "--message" and "--collapse" are specified for "hg rebase", "rebaes.normal" is used as "editform" unexpectedly. Unlike patches before and after in this series for improvement, this is bug fix patch.

ui: invoke editor for committing with HGEDITFORM environment variable At the external editor invocation for committing, the value specified as "editform" for "cmdutil.getcommiteditor" is in "HGEDITFORM". This enables external editor to do own customization according to commit types.

cleanup: name unused variables using convention of leading _ This helps checker tools ... and readability for those who knows and follows the convention.

cleanup: rename check-translation.py checker function - don't hide global var

cleanup: remove some unused / duplicate imports

cleanup: fix some list comprehension redefinitions of existing vars In all the remaining cases the comprehension variable is used for the same thing as a previous loop variable. This will mute some pyflakes "list comprehension redefines" warnings.