on windows, fossil all rebuild causes multiple rebuilds of some repositories.  the duplicate rebuilds have identical paths except for the type of slash used in the path or sometimes the character case.  not every repository gets rebuilt twice, and some can even get rebuilt thrice.  very odd.
<pre>
PS C:\fossil> fossil all rebuild
rebuild
84 (100%)...
rebuild
5637 (100%)...
rebuild
29810 (100%)...
rebuild
33 (100%)...
rebuild
84 (100%)...
rebuild
33 (100%)...
rebuild
29810 (100%)...
rebuild
33 (100%)...
PS C:\fossil> fossil ver
This is fossil version [e2431b17df] 2009-11-09 21:32:36 UTC
</pre>