[tlbuild] Weird "bug" in the build script

[Mojca Miklavec]

Dear Karl & others,

While testing the TL builds I came across a weird "bug" (not critical
in any way). If the machine building the binaries runs out of disk
space, the script exits with code 0 and reports success. (I had a job
setup and wondered why the build was reported as succeeded.)

/path/tobuild/Work/libs/libpng/libpng.a
/path/tobuild/Work/libs/zlib/libz.a libmputil.a -lm
ld: elf error: file upmpost: elf_update: I/O error: output msync: Disc
quota exceeded
collect2: error: ld returned 1 exit status
Makefile:5181: recipe for target 'upmpost' failed
gmake[5]: *** [upmpost] Error 1
gmake[5]: Leaving directory '/path/tobuild/Work/texk/web2c'
Makefile:13449: recipe for target 'all-recursive' failed
gmake[4]: *** [all-recursive] Error 1
gmake[4]: Leaving directory '/path/tobuild/Work/texk/web2c'
Makefile:3822: recipe for target 'all' failed
gmake[3]: *** [all] Error 2
gmake[3]: Leaving directory '/path/tobuild/Work/texk/web2c'
Makefile:901: recipe for target 'recurse' failed
gmake[2]: *** [recurse] Error 1
gmake[2]: Leaving directory '/path/tobuild/Work/texk'
Makefile:481: recipe for target 'all-recursive' failed
gmake[1]: *** [all-recursive] Error 1
gmake[1]: Leaving directory '/path/tobuild/Work/texk'
Makefile:569: recipe for target 'all-recursive' failed
gmake: *** [all-recursive] Error 1
+ echo 2
./Build: exitstatus.txt: cannot create
cat: cannot open exitstatus.txt
done (exit status ) Wed Mar 16 18:28:53 CET 2016
program finished with exit code 0

Mojca