color: be more conservative about setting ANSI mode on Windows (BC) The current color mode detection on Windows assumes the presence of the TERM environment variable assumes ANSI is supported. However, this isn't always true. In MSYS (commonly found as part of MinGW), TERM is set to "cygwin" and the auto resolved color mode of "ansi" results in escape sequences getting printed literally to the terminal. The output is very difficult to read and results in a bad user experience. A workaround is to activate the pager and have it attend all commands (GNU less in MSYS can render ANSI terminal sequences properly). In Cygwin, TERM is set to "xterm." Furthermore, Cygwin supports displaying these terminal sequences properly (unlike MSYS). This patch changes the mode auto-detection logic on Windows to be more conservative about selecting the "ansi" mode. We now only select the "ansi" mode if TERM is set and it contains the string "xterm" or if we were unable to talk to win32 APIs to determine the settings. There is a chance this may take away "ansi" from a terminal that actually supports it. The recourse for this would be to patch the detection to act appropriately and to override color.mode until that patch has landed. However, the author believes this regression is tolerable, since it means MSYS users won't have gibberish printed by default. Since MSYS's common pager (less) supports display of ANSI sequences, there is room to patch the color extensions so it can select the ANSI color mode if a pager is activated. Mozilla (being an active user of MSYS) would really appreciate this being part of the stable branch. However, since I believe it is BC, I haven't explicitly requested application to stable since I figure that request will be denied.