Hmmm...
Not yet sure what to make of that. I was able to download it ok from the Windows side, which accesses the same repository. (Although I did run into a problem with it failing to display the release notes in XTEXT which I'm looking into, but that's unrelated to your situation.)
When I tried it on one of my Linux systems, it looked pretty normal:
.RUN SOSUPD
SOSLIB Update 2.1(117)
Checking for SOSLIB updates...
Creating PPN: /vm/miame/dsk0/908052
New: uspstst.bp[908,052]
New: start.cmd[908,052]
New: delmnu1.bp[908,035]
New: delmnu2.bp[908,035]
New: xtra15.bp[908,021]
Updated: ateapx.sbx[907,006] 1.0(118)
Updated: ateins.sbx[907,006] 2.0(106)
New: strrpl.bsi[907,010]
Updated: inix.sbx[907,031] 5.0(509)
Operation complete; 9 files updated.
See OPR:SOSUPD.TRC and OPR:SOSUPD.LOG for trace/log details
.
Of course that wasn't a fair test because bldzip.cmd[908,48] was already up to date. So I erase it and tried again:
.erase bldzip.cmd[908,48]
Total of 1 file delete, 1 disk block freed.
.run sosupd
SOSLIB Update 2.1(117)
Checking for SOSLIB updates...
New: bldzip.cmd[908,048]
Operation complete; 1 file updated.
See OPR:SOSUPD.TRC and OPR:SOSUPD.LOG for trace/log details
That seems ok too.
And I can't come up with any particular reason for it to single out that file, other than perhaps there was some kind of network problem at the point which wasn't handled as well as it could have been. Does it work when you RUN SOSUPD again?
Actually, I did just remember that there was a problem in an older version of the Fn'HttpGet() function which caused it to fail with extremely small files. So perhaps if you were running an older version of SOSUPD.RUN, which failed to update itself first (that logic was only added in the most recent SOSUPD version - edit 117), then perhaps that would explain it. (And re-running it would work, because on the second go-around, you would be running the latest SOSUPD.RUN.) Or at least that's a theory.
For what it's worth (which may not be much, unless the ISAM file of US zip codes is interesting to you), if you just want the missing file, here's an alternate copy:
BLDZIP.CMD