config: discard "%unset" values defined in the other files read in previously Before this patch, "%unset" can't unset values defined in the other files read in previously, even though online help document says that it can. It can unset only values defined in the same configuration file. For example, the value defined in "~/.hgrc" can't be unset by "%unset" in ".hg/hgrc" of the repository. This patch records "%unset"-ed values in "config.parse()", and discards corresponding values in "config.update()".

tests: rename from test-config-case.t to test-config.t for centralization Before this patch, there is no test script testing configuration handling generally. "test-config-case.t" seems to be specific for testing case sensitive configuration. This patch renames from "test-config-case.t" to "test-config.t" for centralization of tests around configuration handling.

i18n: show the non-ASCII password prompt text correctly Before this patch, the prompt text for asking password is directly passed to "getpass.getpass()" of Python standard library. In "getpass.getpass()" implementation on Windows environment, the prompt text is split into byte sequence and "msvcrt.putch()" is applied on each bytes in it. This splitting causes non-ASCII prompt text to be broken. This patch shows the prompt text for asking password on "ui.getpass()" side, and invokes "getpass.getpass()" with empty prompt text. This prevents non-ASCII prompt text from being broken in "getpass.getpass()" implementation. This patch also sets "ui.prompt" label to prompt text to follow "ui.prompt()" style.