[h-e-w] Odd behavior running a windows executable under emacs 21.3.1

[MBR]

I just upgraded my version of Emacs, and now I'm seeing some very
strange behavior out of the 'ping' command.  Specifically, when I run
ping from a bash shell inside the new version of emacs (21.3.1), it
prints only blank lines, whereas when I run ping from a bash shell
inside the old version of emacs (20.7.1), it displays ping's output
correctly.  Under both versions of emacs, ping produces 12 lines of
output.  If I invoke ping from M-! (which invokes the elisp function
`shell-command'), the output is correct under both versions.

Here's my configuration:
        OS              Windows XP Pro
        Emacs           21.3.1 (Windows port) and 20.7.1 (Windows port)
        Bash            2.05b.0(9)-release (i686-pc-cygwin)
        Ping            version unknown
                        'which ping' reports /cygdrive/c/WINDOWS/system32/ping

Example bash/ping output under emacs 20.7.1:

        bash-2.05b$ ping mit.edu

        Pinging mit.edu [18.7.22.69] with 32 bytes of data:

        Reply from 18.7.22.69: bytes=32 time=14ms TTL=248
        Reply from 18.7.22.69: bytes=32 time=12ms TTL=248
        Reply from 18.7.22.69: bytes=32 time=13ms TTL=248
        Reply from 18.7.22.69: bytes=32 time=12ms TTL=248

        Ping statistics for 18.7.22.69:
            Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
        Approximate round trip times in milli-seconds:
            Minimum = 12ms, Maximum = 14ms, Average = 12ms
        bash-2.05b$

Example bash/ping output under emacs 21.3.1:
        bash-2.05b$ ping mit.edu












        bash-2.05b$

Example M-!/ping output, identical under both emacs 20.7.1 and emacs 21.3.1:

    NOTE: The resulting *Shell Command Output* buffer indicates that
    ping is outputting '\r' as well as '\n' as line terminators, and
    displays the '\r' characters as "^M".  After copying that buffer
    into this email, I replaced all occurrences of '\r' with '^'
    followed by 'M' to guarantee that you'll see the same thing as I'm
    seeing on my screen.

        ^M^M
        Pinging mit.edu [18.7.22.69] with 32 bytes of data:^M^M
        ^M^M
        Reply from 18.7.22.69: bytes=32 time=16ms TTL=248^M^M
        Reply from 18.7.22.69: bytes=32 time=12ms TTL=248^M^M
        Reply from 18.7.22.69: bytes=32 time=13ms TTL=248^M^M
        Reply from 18.7.22.69: bytes=32 time=12ms TTL=248^M^M
        ^M^M
        Ping statistics for 18.7.22.69:^M^M
            Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),^M^M
        Approximate round trip times in milli-seconds:^M^M
            Minimum = 12ms, Maximum = 16ms, Average = 13ms^M^M

Does anyone have any idea why the same ping and bash executables
behave so differently under these two different versions of emacs?

        Mark Rosenthal
        address@hidden