Litian is triggering bash-term-in-posix-shell warnings (use of "source"
command) for some files of the plplot package, like this one:
https://salsa.debian.org/science-team/plplot/-/blob/master/examples/tcl/x00.in
This is a false positive, because this file contains an "exec" command
and the "source" command is placed after it. These are the contents of
the file above, after substitution by the configure script and after
stripping away comments and blank lines:
#!/bin/sh
exec "/usr/bin/pltcl" -f "$0" ${1+"$@"}
source x00.tcl
plinit
x00
plend
Lintian should stop looking for bashisms after the exec command.