X test.fault: understoody why "core file not found"

.nxdtest

@@ -13,7 +13,19 @@ gonprocv = ['1', '2', '']           # GOMAXPROCS=... to test against
 # we don't run test.vg* because there is currently no valgrind on SlapOS.
 for kind in ['t', 'fault', 'asan', 'tsan']:
     t = 'test.%s' % kind
-    TestCase(t, ['make', t])  # TODO summaryf=TAP.summary
+    envadj = {}
+
+    # test.fault: on Ubuntu, when apport is registerd in /proc/sys/kernel/core_pattern,
+    # it is apport which is run to process core. Apport dumps core for us, but
+    # rejects to run in parralel with the following message in its log:
+    #   ERROR: apport ...: another apport instance is already running, aborting
+    # this way, when test.fault tests are run in parallel, some of them fail to
+    # find core corresponding to expected crash.
+    # -> force serial execution to workaround that.
+    if t == 'fault':
+        envadj['MAKEFLAGS'] = '-j1'
+
+    TestCase(t, ['make', t], envadj=envadj)  # TODO summaryf=TAP.summary
 
 # test.py/<stor>-!wcfs runs unit- and functional- tests for wendelin.core in non-wcfs mode.
 for stor in storv:

t/tfault-run

@@ -22,14 +22,6 @@ mkdir "$workdir"
 cd "$workdir"
 
 ulimit -c unlimited
-echo
-echo 'SOFT limits'
-ulimit -a -S
-echo
-echo 'HARD limits'
-ulimit -a -H
-echo
-
 $tfault $arg 2>&1 |tee run.out
 
 grep -q "^# going to fault" run.out     || die "test didn't run to faulting point"