Minor fix for the temporary directory for on-disk cache (#2310)
Minor fix for the temporary directory for on-disk cache (#2310)

If and only if the $TMPDIR env is not set should we try to fallback to
/tmp as the temporary directory for on-disk cache files.
pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,Qining/gapid,Qining/gapid,Qining/gapid,google/gapid,pmuetschard/gapid,google/gapid,Qining/gapid,pmuetschard/gapid,google/gapid,google/gapid,Qining/gapid,google/gapid,google/gapid,pmuetschard/gapid,Qining/gapid,pmuetschard/gapid,pmuetschard/gapid,google/agi,google/gapid,google/agi,google/agi,google/agi,google/agi,google/agi,google/agi,google/agi,google/gapid