Bugzilla

After updating wubkat to only use known good builds, we experienced a weird build failure:

The actual error we're seeing is:
```
Error copying file (if different) from "/mnt/index-scratch/wubkat/git/Source/JavaScriptCore/Scripts/wkbuiltins/builtins_generate_separate_header.py" to "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/builtins_generate_separate_header.py".
[  1%] Generating ../../../WTF/Headers/wtf/ArgumentCoder.h
make[2]: *** [Source/JavaScriptCore/CMakeFiles/JavaScriptCoreSharedScripts.dir/build.make:113: JavaScriptCore/Scripts/builtins_generate_separate_header.py] Error 1
make[2]: *** Deleting file 'JavaScriptCore/Scripts/builtins_generate_separate_header.py'
make[1]: *** [CMakeFiles/Makefile2:1092: Source/JavaScriptCore/CMakeFiles/JavaScriptCoreSharedScripts.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
```

And then this also results in us seeing (but is not the problem, just an effect):
```
Traceback 
(most recent call last):
  File "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/generate-js-builtins.py", line 43, in <module>
    from wkbuiltins import *
  File "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/wkbuiltins.py", line 10, in <module>
    from builtins_generate_separate_header import *
ModuleNotFoundError: No module named 'builtins_generate_separate_header'
```

It's not immediately obvious what's going on.  The file being copied is not the first file to be propagated into the target directory and the source file does seem to exist.  This is also a local-SSD-to-local-SSD operation so the network at least shouldn't be involved (although I guess the local SSD could have issues or maybe experience contention from other VM's?).

This was a very recent commit (only 3 have landed since the commit), so I'm going to do nothing and see what tomorrow's build brings us, but wanted to log what happened.

After updating wubkat to only use known good builds, we experienced a weird build failure:

The actual error we're seeing is:
```
Error copying file (if different) from "/mnt/index-scratch/wubkat/git/Source/JavaScriptCore/Scripts/wkbuiltins/builtins_generate_separate_header.py" to "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/builtins_generate_separate_header.py".
[  1%] Generating ../../../WTF/Headers/wtf/ArgumentCoder.h
make[2]: *** [Source/JavaScriptCore/CMakeFiles/JavaScriptCoreSharedScripts.dir/build.make:113: JavaScriptCore/Scripts/builtins_generate_separate_header.py] Error 1
make[2]: *** Deleting file 'JavaScriptCore/Scripts/builtins_generate_separate_header.py'
make[1]: *** [CMakeFiles/Makefile2:1092: Source/JavaScriptCore/CMakeFiles/JavaScriptCoreSharedScripts.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
```

And then this also results in us seeing (but is not the problem, just an effect):
```
Traceback 
(most recent call last):
  File "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/generate-js-builtins.py", line 43, in <module>
    from wkbuiltins import *
  File "/mnt/index-scratch/wubkat/objdir/JavaScriptCore/Scripts/wkbuiltins.py", line 10, in <module>
    from builtins_generate_separate_header import *
ModuleNotFoundError: No module named 'builtins_generate_separate_header'
```

It's not immediately obvious what's going on.  The file being copied is not the first file to be propagated into the target directory and the source file does seem to exist.  This is also a local-SSD-to-local-SSD operation so the network at least shouldn't be involved (although I guess the local SSD could have issues or maybe experience contention from other VM's?).

This was a very recent commit (only 3 have landed since the commit), so I'm going to do nothing and see what tomorrow's build brings us, but wanted to log what happened.

edit: There were no indications of potential disk space exhaustion, with usage only at 10%.  Also, I should note that it's possible this could have been the same failure encountered earlier in the day that motivated landing bug 1786930, as I did not dig into that log too deeply.