[Bug]: Log file cannot currently be in directory being archived

[forsyth2]

What happened?

Log files can get corrupted if they are in the directory being archived by zstash. See #332 (comment)

What machine were you running on?

Chrysalis

Environment

zstash 1.4.2

Minimal Complete Verifiable Example (MCVE)

# Create zstash archive
mkdir zstash_20240408
echo 'file0 stuff' > zstash_20240408/file0.txt
cd zstash_20240408/
zstash create --hpss=none . 2>&1 | tee 20240408.log

# Now, try to extract it
rm -f 20240408.log file0.txt
zstash extract --hpss=none "*"
For help, please see https://e3sm-project.github.io/zstash. Ask questions at https://github.com/E3SM-Project/zstash/discussions/categories/q-a.
INFO: zstash/000000.tar exists. Checking expected size matches actual size.
INFO: Opening tar archive zstash/000000.tar
INFO: Extracting 20240408.log
ERROR: md5 mismatch for: 20240408.log
ERROR: md5 of extracted file: a8600c75b3d84cdaefd020cf13fb6556
ERROR: md5 of original file:  00a33f0fdfbe470ae5b32123cc3e372c
INFO: Extracting file0.txt
Traceback (most recent call last):
  File "/lcrc/soft/climate/e3sm-unified/base/envs/e3sm_unified_1.9.3_login/lib/python3.10/site-packages/zstash/extract.py", line 535, in extractFiles
    tarinfo: tarfile.TarInfo = tar.tarinfo.fromtarfile(tar)
  File "/lcrc/soft/climate/e3sm-unified/base/envs/e3sm_unified_1.9.3_login/lib/python3.10/tarfile.py", line 1293, in fromtarfile
    obj = cls.frombuf(buf, tarfile.encoding, tarfile.errors)
  File "/lcrc/soft/climate/e3sm-unified/base/envs/e3sm_unified_1.9.3_login/lib/python3.10/tarfile.py", line 1237, in frombuf
    raise InvalidHeaderError("bad checksum")
tarfile.InvalidHeaderError: bad checksum
ERROR: Retrieving file0.txt
ERROR: Encountered an error for files:
ERROR: 20240408.log in 000000.tar
ERROR: file0.txt in 000000.tar
ERROR: The following tar archives had errors:
ERROR: 000000.tar

# Furthermore, try extracting the tar file directly
cd zstash
tar xvf 000000.tar 
20240408.log
tar: Skipping to next header
tar: Exiting with failure status due to previous errors

# The only way to salvage data from the tar file is to use cpio (ironically)
cpio -ivd -H ustar < 000000.tar
././@PaxHeader
20240408.log
cpio: invalid header: checksum error
cpio: warning: skipped 29 bytes of junk
cpio: ././@PaxHeader not created: newer or same age version exists
././@PaxHeader
file0.txt
10 blocks

# At least the data file is recoverable even if the log file is not
cat file0.txt
file0 stuff

Relevant log output

No response

Anything else we need to know?

No response