test_inherit_env fail when using TESTNAME on windows

[oli-obk]

the command i ran was

make check TESTNAME=test_inherit_env RUST_TEST_TASKS=1

i ran into the error due to trying to check for a specific test, but that didn't work (all tests were run, probably due to the same problem).

the environment variable contains

MAKEFLAGS= -- RUST_TEST_TASKS=1 ?TESTNAME=test_inherit_env

but expected is

MAKEFLAGS= -- RUST_TEST_TASKS=1 TESTNAME=test_inherit_env

not sure where the questionmark comes from.

full log of the test (removed some due to privacy)

thread '<unnamed>' panicked at 'output doesn't contain `MAKEFLAGS= -- RUST_TEST_TASKS=1 TESTNAME=test_inherit_env`
!;=;\
ALLUSERSPROFILE=C:\ProgramData
APR_ICONV_PATH=C:\Program Files (x86)\Subversion\iconv
CFG_BUILD=x86_64-pc-windows-gnu
CFG_BUILD_DIR=D:/rust/
CFG_LIBDIR=C:/msys64/usr/local/bin
CFG_LIBDIR_RELATIVE=bin
CFG_PACKAGE_NAME=rustc-1.0.0-dev
CFG_PREFIX=C:/msys64/usr/local
CFG_RELEASE=1.0.0-dev
CFG_SRC_DIR=D:/rust/
CFG_VERSION=1.0.0-dev (268755e27 2015-01-07 10:23:17 +0100)
CFG_VERSION_WIN=1.0.0
CFG_VER_DATE=2015-01-07 10:23:17 +0100
CFG_VER_HASH=268755e2767b3de8b3cd3a4c944a465e4ada8214
CLASSPATH=.;D:\antlr-4.2-complete.jar
COMMONPROGRAMFILES=C:\Program Files\Common Files
COMSPEC=C:\Windows\system32\cmd.exe
CommonProgramFiles(x86)=C:\Program Files (x86)\Common Files
CommonProgramW6432=C:\Program Files\Common Files
EDITOR=notepad++
FP_NO_HOST_CHECK=NO
GNADE_BASEPATH=C:\GNADE
GRAPHVIZ_DOT=D:\mbeddr\tools\graphviz\bin\dot.exe
HOMEPATH=\
INFOPATH=C:\msys64\usr\local\info;C:\msys64\usr\share\info;C:\msys64\usr\info;C:\msys64\share\info
JAVA_HOME=C:\Program Files\Java\jre1.8.0_25\
LANG=de_DE.UTF-8
LC_ALL=C
MAKEFLAGS= -- RUST_TEST_TASKS=1 ?TESTNAME=test_inherit_env
MAKELEVEL=1
MAKEOVERRIDES=${-*-command-variables-*-}
MAKE_TERMERR=/dev/pty0
MAKE_TERMOUT=/dev/pty0
MANPATH=C:\msys64\mingw64\share\man;C:\msys64\usr\local\man;C:\msys64\usr\share\man;C:\msys64\usr\man;C:\msys64\share\man
MSYSCON=mintty.exe
MSYSTEM=MINGW64
NUMBER_OF_PROCESSORS=4
OS=Windows_NT
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.PY
PKG_CONFIG_PATH=C:/msys64/mingw64/lib/pkgconfig
PROCESSOR_ARCHITECTURE=AMD64
PROCESSOR_IDENTIFIER=Intel64 Family 6 Model 58 Stepping 9, GenuineIntel
PROCESSOR_LEVEL=6
PROCESSOR_REVISION=3a09
PROGRAMFILES=C:\Program Files
PROMPT=$P$G
PWD=D:/rust
ProgramData=C:\ProgramData
ProgramFiles(x86)=C:\Program Files (x86)
ProgramW6432=C:\Program Files
RUST_TEST_TASKS=1
SESSIONNAME=Console
SHELL=C:/msys64/usr/bin/bash
SHLVL=2
SYSTEMDRIVE=C:
SYSTEMROOT=C:\Windows
TEMP=C:\msys64\tmp
TERM=xterm-256color
TMP=C:\msys64\tmp
WD=C:\msys64\usr\bin\
WINDIR=C:\Windows
_=x86_64-pc-windows-gnu/stage2/test/stdtest-x86_64-pc-windows-gnu.exe
configsetroot=C:\Windows\ConfigSetRoot
windows_tracing_flags=3
windows_tracing_logfile=C:\BVTBin\Tests\installpackage\csilogfile.log
', D:\rust\src\libstd\io\process.rs:1065
test io::process::tests::test_inherit_env ... FAILED

[oli-obk]

this works again in master