CMake generates bad command with ninja using rsp files

CMake (3.6.1 and 3.7.0) have generated a rules file which contains a error in one of our linker rules using Ninja (v 1.7.2).

The following generated command (from rules.ninja) is the BAD example (fails):

rule CXX_STATIC_LIBRARY_LINKER__MyLib
  command = cmd.exe /C "$PRE_LINK && C:\ARM\ARMCT_5.0x\bin\armar.exe --create -cr $TARGET_FILE $LINK_FLAGS @$RSP_FILE && $POST_BUILD"
  description = Linking CXX static library $TARGET_FILE
  rspfile = $RSP_FILE
  rspfile_content = $in_newline $LINK_PATH $LINK_LIBRARIES
  restat = $RESTAT

The following generated but modifyed command (from rules.ninja) is the GOOD example (works):

rule CXX_STATIC_LIBRARY_LINKER__MyLib
  command = cmd.exe /C "$PRE_LINK && C:\ARM\ARMCT_5.0x\bin\armar.exe --create -cr $TARGET_FILE $LINK_FLAGS $RSP_FILE && $POST_BUILD"
  description = Linking CXX static library $TARGET_FILE
  rspfile = $RSP_FILE
  rspfile_content = $in_newline $LINK_PATH $LINK_LIBRARIES
  restat = $RESTAT

You can see that the bad example contains an '@' in the 'command' where the RSP_FILE is specifyed. This will fail the armar.exe because it can not resolve the bad path. Removing the '@' will solve the problem.

This Bug is a Blocker.