$ ./fork-kernels.sh 
+ source ./functions.sh
+ cd ..
+ rm -rf pijul-tests-data
+ mkdir pijul-tests-data
+ cd pijul-tests-data
+ pijul init repo
+ cd repo
+ tar -xJf ../../pijul-tests/kernel/linux-2.0.1.tar.xz --strip-components=1
+ stat Makefile
  File: Makefile
  Size: 9589      	Blocks: 24         IO Block: 4096   regular file
Device: 254,0	Inode: 133141      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/   mpech)   Gid: ( 1001/   mpech)
Access: 2022-07-25 12:45:13.086220468 +0300
Modify: 1996-06-10 08:15:28.000000000 +0300
Change: 2022-07-25 12:45:13.086220468 +0300
 Birth: 2022-07-25 12:45:13.086220468 +0300
+ add
+ pijul add -r .
+ record
+ pijul record -am.
+ head Makefile
VERSION = 2
PATCHLEVEL = 0
SUBLEVEL = 1

ARCH = i386

#
# For SMP kernels, set this. We don't want to have this in the config file
# because it makes re-config very ugly and too many fundamental files depend
# on "CONFIG_SMP"
+ pijul fork 2
+ pijul channel switch 2
Outputting repository ←                                                                                                  
+ tar -xJf ../../pijul-tests/kernel/linux-2.0.2.tar.xz --strip-components=1
+ stat Makefile
  File: Makefile
  Size: 9589      	Blocks: 24         IO Block: 4096   regular file
Device: 254,0	Inode: 133141      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/   mpech)   Gid: ( 1001/   mpech)
Access: 2022-07-25 12:45:15.726309229 +0300
Modify: 1996-07-03 22:06:38.000000000 +0300
Change: 2022-07-25 12:45:15.726309229 +0300
 Birth: 2022-07-25 12:45:15.726309229 +0300
+ add
+ pijul add -r .
+ record
+ pijul record -am.
Nothing to record
+ pijul channel switch main
Outputting repository ←                                                                                                  
+ head Makefile
VERSION = 2
PATCHLEVEL = 0
SUBLEVEL = 2

ARCH = i386

#
# For SMP kernels, set this. We don't want to have this in the config file
# because it makes re-config very ugly and too many fundamental files depend
# on "CONFIG_SMP"
+ echo OK--fork-kernels
OK--fork-kernels
$

I assume this place is wrong:

...
+ pijul record -am.
Nothing to record
...

There are many changes between kernels 2.0.1 and 2.0.2.

Minimum Makefile is changed, looks like modified mtime is not detected.

Fixed, thanks!