How do I find the Unescaped character?

I'm getting some error messages from b2  when building Boost 1.67.
If I pipe the output of the build to a file the errors are much less likely to occur.
Any idea what might be casing this?

Many Thanks,

Brian Kuhl
Wind River

../b2 -j1 --prefix=/yow-build40-lx1/bkuhl/workspace/vsbSR540/usr/root --libdir=/yow-build40-lx1/bkuhl/workspace/vsbSR540/usr/lib/common --includedir=/yow-build40-lx1/bkuhl/workspace/vsbSR540/usr/h/public    toolset=gcc cross-compile=vxworks --reconfigure  link=static "testing.execute=off"   "--limit-tests=algorithm" "--exclude-tests=coroutine2|function_types|functional|iostreams|logic|rational" -d2
/yow-build40-lx1/bkuhl/workspace/vsbSR540/3pp/BOOST/boost_1_67_0/libs/predef/check/../tools/check/predef.jam:46: Unescaped special character in argument $(language)::$(expression)
../libs/algorithm/test/Jamfile.v2:19: Unescaped special character in argument algorithm:
../libs/algorithm/minmax/test/Jamfile.v2:18: Unescaped special character in argument algorithm/minmax:
../libs/contract/test/Jamfile.v2:417: Unescaped special character in argument <define>BOOST_CONTRACT_ON_MISSING_CHECK_DECL="{ throw err(); }"
../libs/lexical_cast/test/Jamfile.v2:35: Unescaped special character in argument <cxxflags>/Zc:wchar_t-

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