alr publish --tar on Windows fails in step 5: Deploy sources. Error message is:

Publishing assistant: step 5 of 8: Deploy sources
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Success: Computed hash: sha256:d5a89e26beae0bc03ad18a0b0d1d3d75f87c32047879d25da11970cb5c4662a3
Success: Computed hash: sha512:42e53d96e5961e95b7a984d9c9778a1d3bd8ee0c87b8b3b515fa31f67c2d073c8565afc2f4b962c43668c4efa1e478da9bb0ecffa79479c7e880731bc4c55765
Warning: tar failed: Command ["tar", "-x", "-f", "C:\Projects\org.stephe_leake.sal\alr-vtyx.tmp\stephes_ada_library-3.7.0.tgz"] exited with code 128 and output: /usr/bin/tar: Cannot connect to C: resolve failed
ERROR: alire-publish.adb:901 finalize/adjust raised exception
ERROR: alr encountered an unexpected error, re-run with -d for details.

With -d:
stderr: Command ["tar", "--force-local", "-x", "-f", "C:\Projects\org.stephe_leake.sal\alire\tmp\alr-ebrn.tmp\stephes_ada_library-3.7.0.tgz"] exited with code 2 and output: \ngzip: stdin: not in gzip format\n/usr/bin/tar: Child returned status 1\n/usr/bin/tar: Error is not recoverable: exiting now
stderr: Command ["tar", "-x", "-f", "C:\Projects\org.stephe_leake.sal\alire\tmp\alr-ebrn.tmp\stephes_ada_library-3.7.0.tgz"] exited with code 128 and output: /usr/bin/tar: Cannot connect to C: resolve failed
Warning: tar failed: Command ["tar", "-x", "-f", "C:\Projects\org.stephe_leake.sal\alire\tmp\alr-ebrn.tmp\stephes_ada_library-3.7.0.tgz"] exited with code 128 and output: /usr/bin/tar: Cannot connect to C: resolve failed
stderr: Command ["attrib", "-R", "/D", "/S", "C:\Projects\org.stephe_leake.sal\alire\tmp\alr-ebrn.tmp*"] exited with code -1
stderr: ALIRE.CHECKED_ERROR
stderr: Command ["attrib", "-R", "/D", "/S", "C:\Projects\org.stephe_leake.sal\alire\tmp\alr-ebrn.tmp*"] exited with code -1
stderr: raised ALIRE.CHECKED_ERROR : alire-stored-error:3
[C:\home\stephe\bin\alr.exe]
0xdc8cdb Semantic_Versioning.Basic.At_Least at alire.adb:251
0xa63c02 Semantic_Versioning.Basic.At_Least at alire-os_lib-subprocess.adb:110
0x79a1c8 Semantic_Versioning.Basic.At_Least at alire-directories.adb:229
0x79f127 Semantic_Versioning.Basic.At_Least at alire-directories.adb:518
0x795916 Semantic_Versioning.Basic.At_Least at alire-directories.ads:221
0x98ee75 Semantic_Versioning.Basic.At_Least at alire-origins-deployers-source_archive.adb:284
0x98db4d Semantic_Versioning.Basic.At_Least at alire-origins-deployers-source_archive.adb:263
0x98b183 Semantic_Versioning.Basic.At_Least at alire-origins-deployers-source_archive.adb:106
0xb54269 Semantic_Versioning.Basic.At_Least at alire-publish.adb:385
0xb5e5e8 Semantic_Versioning.Basic.At_Least at alire-publish.adb:893
0xb5ed5e Semantic_Versioning.Basic.At_Least at alire-publish.adb:916
0x49f2a3 Semantic_Versioning.Basic.At_Least at alr-commands-publish.adb:49
0x51c0a3 Semantic_Versioning.Basic.At_Least at clic-subcommand-instance.adb:742
0x528a27 Semantic_Versioning.Basic.At_Least at alr-commands.adb:492
0x401761 Alr.Main at alr-main.adb:10
0x404bd6 Main at b__alr-main.adb:2130
0x401423 __tmainCRTStartup at ???
0x40113b mainCRTStartup at ???
[C:\WINDOWS\System32\KERNEL32.DLL]
0x7ff886b57032
[C:\WINDOWS\SYSTEM32\ntdll.dll]
0x7ff888a6269f

Apparently it's using msys tar, but giving it a Windows directory name.