I was attempting to use darcs as a backend for etckeeper. But during 
etckeeper's initialization, while running the initial 

darcs add -qr . 

from /etc, darcs returns 

darcs: Maybe.fromJust: Nothing

while processing the usb_modeswitch.d directory, which contains unusual file 
names, such as 

0af0:7311
19d2:0101

and

05c6:1000:uMa=AnyDATA
05c6:1000:uMa=SAMSUNG
05c6:1000:uMa=Vertex
16d8:6803:?

Attempting to add one of these by hand results in darcs warning that the 
filename is not windows compatible, and --reserved-ok needs to be added to the 
command line.

When --reserved-ok is present while trying to add one of the file with an '=' 
in the name, darcs chokes with fromJust: Nothing. It works fine for filenames 
containing question marks.

If I've got some free time, I'll take a look at the source and see if I can 
supply a patch.

cheers,

kirstin

-- 
Colors may fade in time.

Hi Kirstin,

Thank-you for potentially volunteering to look into this bug!  Could I
suggest boiling it down into a formal test case first?  

See http://wiki.darcs.net/Development/RegressionTests

Bugs on our tracker seem to settling on a cycle of 
0. get missing info, clarifications from poster (waiting-for)
1. create test (need-action) <-- we are here
2. diagnose bug (need-action)
3. go hack (need-implementation)

I'm assigning you for now just so we know who to chase up on; if you
find yourself too busy to look into this, please feel free to unassign
yourself!

Cheers,

Eric

I would dare to say that '=' is not a cause for this bug, the real 
culrpit is the ':'.

See issue1932 (it even mentions the same filenames)