Possible memory error in `expand_path`

[nsoblath]

Brent inconsistently sees glibc errors when running Katydid through his hep cluster docker.

It appears to depend on what directory he is running Katydid from.

Here's one example:

[root@083cdbebca13 stalled_job]# Katydid -c TrackFinding-Multipeak_withEggHeader_mat.yaml -e rid000001984_evts000420-000434.mat --rootw.output-file=rid000001984_evts000420-000434.root --h5w.output-file=rid000001984_evts000420-000434.h5
17:07:14 [ PROG] /Main/Katydid.cc(23): Welcome to Katydid!
*** glibc detected *** Katydid: munmap_chunk(): invalid pointer: 0x00000000032239d0 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x75dee)[0x7f9ec3697dee]
/lib64/libc.so.6(wordfree+0x39)[0x7f9ec36f6429]
/cvmfs/hep.pnnl.gov/project8/katydid-2.6.7/build/lib/libScarab_Nymph_Katydid.so(_ZN6scarab11expand_pathERKSs+0x59)[0x7f9ec4170ff9]
/cvmfs/hep.pnnl.gov/project8/katydid-2.6.7/build/lib/libScarab_Nymph_Katydid.so(_ZN6scarab16param_translator9read_fileERKSsPKNS_10param_nodeE+0x193)[0x7f9ec41809a3]
/cvmfs/hep.pnnl.gov/project8/katydid-2.6.7/build/lib/libNymph_Katydid.so(_ZN5Nymph13KTApplicationC1EiPPcbPN6scarab10param_nodeE+0x5b5)[0x7f9ec441c035]
/cvmfs/hep.pnnl.gov/project8/katydid-2.6.7/build/lib/libKatydidUtility.so(_ZN7Katydid12KTKatydidAppC1EiPPcbbPN6scarab10param_nodeE+0x17)[0x7f9ec48b7ef7]
Katydid(_ZNSt12__shared_ptrIN7Katydid12KTKatydidAppELN9__gnu_cxx12_Lock_policyE2EEC2ISaIS1_EIRiRPPcEEESt19_Sp_make_shared_tagRKT_DpOT0_+0x60)[0x4035b0]
Katydid(main+0x1a7)[0x4037b7]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x7f9ec3640d1d]
Katydid[0x402f89]

. . . followed by a memory map that was not copied.