#2148 7za.exe cannot extract zip file with zNN extension

[Vasya Pupkin]

How to reproduce:

1. Create a zip archive test.zip containing non-empty file test.dat
2. Rename test.zip to test.z99
3. Run 7za.exe e -tzip -sae -y test.z99

Expected behavior:

1. File test.dat is extracted

Actual behavior:

1. File test.dat is extracted
2. An error "Unavailable data: test.dat" appears
3. Extracted file test.dat is empty

Here's a complete output:
D:\temp>7ZA.EXE e -tzip -sae -y test.z99

7-Zip (a) 18.05 (x86) : Copyright (c) 1999-2018 Igor Pavlov : 2018-04-30

Scanning the drive for archives:
1 file, 53053 bytes (52 KiB)

Extracting archive: test.z99

ERRORS:
Headers Error
ERRORS:
Missing volume : test.zip

--
Path = test.z99
Type = zip
ERRORS:
Headers Error
ERROR = Missing volume : test.zip
Physical Size = 53053
Characteristics = Local Central
Total Physical Size = 53053
Multivolume = +
Volume Index = 98
Volumes = 99

ERROR: Unavailable data : test.dat

Sub items Errors: 1

Archives with Errors: 1

Open Errors: 2

Sub items Errors: 1

[Vasya Pupkin]

Please note that -sae switch is given on command line. One would expect that this switch disables extension processing and no "magic heuristics" are being done based on extension. Instead 7-zip decides that this file is a part of multi-volume archive and fails to extract data properly.

[Igor Pavlov]

Not a BUG
7-Zip looks extension and tries to find another parts.

[Vasya Pupkin]

Well, since all other unpackers including iconic pkunzip extract files from such archive without issues, I consider this a bug. It is fine to print a warning, but to overwrite extracted file with empty file on extraction is not something that should be called not a bug.