Fixed make distclean not clean gpMgmt (#3976)
Fixed make distclean not clean gpMgmt (#3976)

After python version updated, gpdb report build problem even after 'make distclean'.
The root cause is shell command broken because multiple python versions directories in below:
    gpMgmt/bin/pythonSrc/subprocess32
    gpMgmt/bin/pythonSrc/PyGreSQL-4.0/build/lib.linux
yuanzhao/gpdb,yuanzhao/gpdb,yuanzhao/gpdb,jmcatamney/gpdb,adam8157/gpdb,Chibin/gpdb,edespino/gpdb,edespino/gpdb,greenplum-db/gpdb,xinzweb/gpdb,ashwinstar/gpdb,adam8157/gpdb,edespino/gpdb,adam8157/gpdb,xinzweb/gpdb,ashwinstar/gpdb,edespino/gpdb,50wu/gpdb,yuanzhao/gpdb,lisakowen/gpdb,jmcatamney/gpdb,yuanzhao/gpdb,edespino/gpdb,50wu/gpdb,jmcatamney/gpdb,lisakowen/gpdb,yuanzhao/gpdb,Chibin/gpdb,lisakowen/gpdb,lisakowen/gpdb,adam8157/gpdb,xinzweb/gpdb,greenplum-db/gpdb,jmcatamney/gpdb,lisakowen/gpdb,yuanzhao/gpdb,Chibin/gpdb,Chibin/gpdb,yuanzhao/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,greenplum-db/gpdb,greenplum-db/gpdb,edespino/gpdb,xinzweb/gpdb,Chibin/gpdb,adam8157/gpdb,lisakowen/gpdb,xinzweb/gpdb,jmcatamney/gpdb,50wu/gpdb,yuanzhao/gpdb,lisakowen/gpdb,Chibin/gpdb,adam8157/gpdb,ashwinstar/gpdb,ashwinstar/gpdb,xinzweb/gpdb,ashwinstar/gpdb,Chibin/gpdb,50wu/gpdb,lisakowen/gpdb,Chibin/gpdb,adam8157/gpdb,Chibin/gpdb,Chibin/gpdb,edespino/gpdb,50wu/gpdb,edespino/gpdb,yuanzhao/gpdb,ashwinstar/gpdb,jmcatamney/gpdb,edespino/gpdb,jmcatamney/gpdb,edespino/gpdb,jmcatamney/gpdb,greenplum-db/gpdb,xinzweb/gpdb,50wu/gpdb,ashwinstar/gpdb,adam8157/gpdb,50wu/gpdb,greenplum-db/gpdb,ashwinstar/gpdb