Bug#1003427: Acknowledgement (COMPRESS=zstd and COMPRESS=lz4 hard-coded to bad COMPRESSLEVELs)

[Trent W. Buck]

PS: my previous email speculated: does zstd -T0 break SOURCE_DATE_EPOCH?
I think this test shows that zstd -T0 is safe even when SOURCE_DATE_EPOCH=1.
i.e. it does not need the equivalent of mkinitramfs's workaround for xz and 
gzip.

    bash5$ ls -hl
    total 1.1G
    -rw-r--r-- 1 twb twb 1.1G 2022-01-10 11:06 linux_5.15.5.orig.tar

    bash5$ zstd --keep --fast --verbose --threads=0 linux_5.15.5.orig.tar
    *** zstd command line interface 64-bits v1.4.8, by Yann Collet ***
    Note: 4 physical core(s) detected
    linux_5.15.5.orig.tar : 21.38%   (1136691200 => 243006203 bytes, 
linux_5.15.5.orig.tar.zst)

    bash5$ ls
    linux_5.15.5.orig.tar  linux_5.15.5.orig.tar.zst

    bash5$ mv linux_5.15.5.orig.tar.zst linux_5.15.5.orig.tar.zst.~1~

    bash5$ zstd --keep --fast --verbose --threads=0 linux_5.15.5.orig.tar
    *** zstd command line interface 64-bits v1.4.8, by Yann Collet ***
    Note: 4 physical core(s) detected
    linux_5.15.5.orig.tar : 21.38%   (1136691200 => 243006203 bytes, 
linux_5.15.5.orig.tar.zst)

    bash5$ mv linux_5.15.5.orig.tar.zst linux_5.15.5.orig.tar.zst.~2~

    bash5$ b2sum *~
    
570c5509c9c95dabb655be223f70d48182ee547da3df43696139f00969e3eeb51b4f0a5bab9ca3e905ba3e52fbebb6892ee643e246522198b764143228e81437
  linux_5.15.5.orig.tar.zst.~1~
    
570c5509c9c95dabb655be223f70d48182ee547da3df43696139f00969e3eeb51b4f0a5bab9ca3e905ba3e52fbebb6892ee643e246522198b764143228e81437
  linux_5.15.5.orig.tar.zst.~2~

    bash5$ SOURCE_DATE_EPOCH=1 zstd --keep --verbose --threads=0 
linux_5.15.5.orig.tar
    *** zstd command line interface 64-bits v1.4.8, by Yann Collet ***
    Note: 4 physical core(s) detected
    linux_5.15.5.orig.tar : 16.29%   (1136691200 => 185188738 bytes, 
linux_5.15.5.orig.tar.zst)

    bash5$ ls -lh
    total 1.7G
    -rw-r--r-- 1 twb twb 1.1G 2022-01-10 11:06 linux_5.15.5.orig.tar
    -rw-r--r-- 1 twb twb 177M 2022-01-10 11:06 linux_5.15.5.orig.tar.zst
    -rw-r--r-- 1 twb twb 232M 2022-01-10 11:06 linux_5.15.5.orig.tar.zst.~1~
    -rw-r--r-- 1 twb twb 232M 2022-01-10 11:06 linux_5.15.5.orig.tar.zst.~2~

    bash5$ mv linux_5.15.5.orig.tar.zst linux_5.15.5.orig.tar.zst.~1~

    bash5$ SOURCE_DATE_EPOCH=1 zstd --keep --verbose --threads=0 
linux_5.15.5.orig.tar
    *** zstd command line interface 64-bits v1.4.8, by Yann Collet ***
    Note: 4 physical core(s) detected
    linux_5.15.5.orig.tar : 16.29%   (1136691200 => 185188738 bytes, 
linux_5.15.5.orig.tar.zst)

    bash5$ mv linux_5.15.5.orig.tar.zst linux_5.15.5.orig.tar.zst.~2~

    bash5$ b2sum *~
    
7edc85faf5c53c62d2a7b13f58100f2795aee109092bbf728c763d1945c84797cb71a4ae32f1cfd53fdaea959120dbbe6eea47fcdb4ee67a5e71faea7e1a122a
  linux_5.15.5.orig.tar.zst.~1~
    
7edc85faf5c53c62d2a7b13f58100f2795aee109092bbf728c763d1945c84797cb71a4ae32f1cfd53fdaea959120dbbe6eea47fcdb4ee67a5e71faea7e1a122a
  linux_5.15.5.orig.tar.zst.~2~