appimagetool -r removes wrong file if AppImage path is not the full canonical path

[mklein-de]

if appimageupdatetool is given a relative path to the AppImage, -r removes
the freshly updated .AppImage (and keeps .AppImage.zs-old):

$ appimageupdatetool -r XXXXXXXXXX-latest-x86_64.AppImage
Checking for updates...
... done!
Starting update...

Updating from generic server via ZSync
zsync2: /XXXX/XXXXXXX/XXXXXXXXXX/XXXXX/XXXXXXXXXX-latest-x86_64.AppImage found, using as seed file
zsync2: Target file: /XXXX/XXXXXXX/XXXXXXXXXX/XXXXX/XXXXXXXXXX-latest-x86_64.AppImage
zsync2: Reading seed file: /XXXX/XXXXXXX/XXXXXXXXXX/XXXXX/XXXXXXXXXX-latest-x86_64.AppImage
43.3802% done (15.97 of 36.81 MiB)...
zsync2: Reading seed file: XXXXXXXXXX-latest-x86_64.AppImage
99.69% done (36.69 of 36.81 MiB)...
zsync2: Usable data from seed files: 99.686920%
zsync2: Renaming temp file
zsync2: Fetching remaining blocks
zsync2: Downloading from http://XXXXXXXXXXXXXXXX/XXXXXXXXXX/linux/XXXXXXXXXX-latest-x86_64.AppImage
zsync2: optimized ranges, old requests count 3, new requests count 2

zsync2: Verifying downloaded file
100.00% done (36.81 of 36.81 MiB)...
zsync2: checksum matches OK
0.00% done (0.00 of 36.81 MiB)...
zsync2: used 38473728 local, fetched 128192
100.00% done (36.81 of 36.81 MiB)...
Validation warning: AppImage not signed
Removing old AppImage: /XXXX/XXXXXXX/XXXXXXXXXX/XXXXX/XXXXXXXXXX-latest-x86_64.AppImage
Update successful. New file created: /XXXX/XXXXXXX/XXXXXXXXXX/XXXXX/XXXXXXXXXX-latest-x86_64.AppImage

Full (canonical) path removes .AppImage.zs-old:

$ appimageupdatetool -r $PWD/XXXXXXX-latest-x86_64.AppImage            
Checking for updates...
... done!
Starting update...

Updating from generic server via ZSync
zsync2: /XXXXXXX/XXXXXXX/XXXXXXX/XXXXX/XXXXXXX-latest-x86_64.AppImage found, using as seed file
zsync2: Target file: /XXXXXXX/XXXXXXX/XXXXXXX/XXXXX/XXXXXXX-latest-x86_64.AppImage
zsync2: Reading seed file: /XXXXXXX/XXXXXXX/XXXXXXX/XXXXX/XXXXXXX-latest-x86_64.AppImage
36.243% done (13.34 of 36.81 MiB)...
zsync2: Usable data from seed files: 99.686920%
zsync2: Renaming temp file
zsync2: Fetching remaining blocks
zsync2: Downloading from http://XXXXXXXXXXXXXXXX/XXXXXXX/linux/XXXXXXX-latest-x86_64.AppImage
zsync2: optimized ranges, old requests count 3, new requests count 2

zsync2: Verifying downloaded file
100.00% done (36.81 of 36.81 MiB)...
zsync2: checksum matches OK
0.00% done (0.00 of 36.81 MiB)...
zsync2: used 38473728 local, fetched 128192
100.00% done (36.81 of 36.81 MiB)...
Validation warning: AppImage not signed
Removing old AppImage: /XXXXXXX/XXXXXXX/XXXXXXX/XXXXX/XXXXXXX-latest-x86_64.AppImage.zs-old
Update successful. New file created: /XXXXXXX/XXXXXXX/XXXXXXX/XXXXX/XXXXXXX-latest-x86_64.AppImage