merge with stable

posix: quote the specified string only when it may have to be quoted This patch makes "posix.shellquote" examine the specified string and quote it only when it may have to be quoted for safety, like as the previous patch for "windows.shellquote". In fact, on POSIX environment, quoting itself doesn't cause issues like issue4463. But (almost) equivalent quoting policy can avoid examining test result differently on POSIX and Windows (even though showing command line with "%r" causes such examination in "test-extdiff.t"). The last hunk for "test-extdiff.t" in this patch isn't needed for the previous patch for "windows.shellquote", because the code path of it is executed only "#if execbit" (= avoided on Windows).

windows: quote the specified string only when it has to be quoted Before this patch, "windows.shellquote" (as used as "util.shellquote") always quotes specified strings with double quotation marks, for external process invocation. But some problematic applications can't work correctly, when command line arguments are quoted: see issue4463 for detail. On the other hand, quoting itself is needed to specify arguments containing whitespaces and/or some special characters exactly. This patch makes "windows.shellquote" examine the specified string and quote it only when it may have to be quoted for safety.

extdiff: rename the name of an argument for readability To reduce amount of changes for review-ability, previous patch uses "args" as argument name of "dodiff()", even though "args" includes also the name of command to be executed (or full-path of it). This patch replaces "args" by more appropriate name "cmdline".

extdiff: avoid unexpected quoting arguments for external tools (issue4463) Before this patch, all command line arguments for external tools are quoted by the combination of "shlex.split" and "util.shellquote". But this causes some problems. - some problematic commands can't work correctly with quoted arguments For example, 'WinMerge /r ....' is OK, but 'WinMerge "/r" ....' is NG. See also below for detail about this problem. https://bitbucket.org/tortoisehg/thg/issue/3978/ - quoting itself may change semantics of arguments For example, when the environment variable CONCAT="foo bar baz': - mydiff $CONCAT => mydiff foo bar baz (taking 3 arguments) - mydiff "$CONCAT" => mydiff "foo bar baz" (taking only 1 argument) For another example, single quoting (= "util.shellquote") on POSIX environment prevents shells from expanding environment variables, tilde, and so on: - mydiff "$HOME" => mydiff /home/foobar - mydiff '$HOME' => mydiff $HOME - "shlex.split" can't handle some special characters correctly It just splits specified command line by whitespaces. For example, "echo foo;echo bar" is split into ["echo", "foo;echo", "bar"]. On the other hand, if quoting itself is omitted, users can't specify options including space characters with "--option" at runtime. The root cause of this issue is that "shlex.split + util.shellquote" combination loses whether users really want to quote each command line elements or not, even though these can be quoted arbitrarily in configurations. To resolve this problem, this patch does: - prevent configurations from being processed by "shlex.split" and "util.shellquote" only (possibly) "findexe"-ed or "findexternaltool"-ed command path is "util.shellquote", because it may contain whitespaces. - quote options specified by "--option" via command line at runtime This patch also makes "dodiff()" take only one "args" argument instead of "diffcmd" and "diffopts. It also omits applying "util.shellquote" on "args", because "args" should be already stringified in "extdiff()" and "mydiff()". The last hunk for "test-extdiff.t" replaces two whitespaces by single whitespace, because change of "' '.join()" logic causes omitting redundant whitespaces.

subrepo: add forgotten annotation for reverting git subrepos Support for reverting git subrepos was added earlier, but the annotation to handle any subrepo errors was forgotten.

subrepo: add full revert support for git subrepos Previously, revert was only possible if the '--no-backup' switch was specified. Now, to support backups, we explicitly go over all modified files in the subrepo.

setup: don't fail when Python doesn't have the cygwinccompiler package Some Python installations like the ones available from the optware project for the Synology DiskStation NASes don't have that package, which means running the setup script will crash and exit right away. Instead, we now just use an empty/fake class for the HackedMingw32CCompiler, which we likely won't use anyway.