[tex-eplain] bug in eplain 3.8

[Ottmar Loos]

Dear all:

It seems that there is a bug in eplain, version 3.8:  the command

\providecommand

fails with the error message

!!! Undefined control sequence.
<recently read> \@optionalusercs

This is unfortunate as \providecommand appears in .bbl files generated by
bibtex.  As a stopgap measure, I have used 

\let \providecommand \newcommand

which is good enough for the bbl files.

Strangely enough, the bug does not occur in eplain, versions 3.4 to 3.7.

I have had a look at the differences between 3.7 and 3.8, but, not being much
of a TeX expert, could not locate the source of the error.

Any comments are highly appreciated.

Sincerely,
Ottmar Loos