tests: restore 'python' and '$TESTDIR/' for dummyssh invocation
This is a backout of
46727fea7a00, and a partial backout of
c3ecbf694904.
Windows won't execute 'dummyssh' directly, presumably because CreateProcess()
doesn't know how to execute a bash script:
$ hg clone -e "dummyssh" ssh://user@dummy/cloned sshclone
remote: 'dummyssh' is not recognized as an internal or external command,
remote: operable program or batch file.
abort: no suitable response from remote hg!
[255]
With the restoration of python as the executable, $TESTDIR needs to be restored
for these invocations, because python won't search $PATH for 'dummyssh':
$ hg clone -e "python dummyssh" ssh://user@dummy/cloned sshclone
remote: python: can't open file 'dummyssh': [Errno 2] No such file or directory
abort: no suitable response from remote hg!
[255]
perf: support -T for every perf commands
We are already building a formatter, we can now pass it options the official
way.