ctests: move issue with nomenclature insets to a dedicated test case.

iconv fails, if a nomenclature inset contains an uncodable character
This led to failure of the indonesian UserGuide in the attic.
Fix it there and add a minimal, specific test sample instead.

autotests/export/latex/iconv-error-nomenclature.lyx

@@ -0,0 +1,149 @@
+#LyX 2.3 created this file. For more info see http://www.lyx.org/
+\lyxformat 542
+\begin_document
+\begin_header
+\save_transient_properties true
+\origin unavailable
+\textclass article
+\use_default_options true
+\maintain_unincluded_children false
+\language english
+\language_package default
+\inputencoding auto
+\fontencoding global
+\font_roman "lmodern" "default"
+\font_sans "default" "default"
+\font_typewriter "default" "default"
+\font_math "auto" "auto"
+\font_default_family default
+\use_non_tex_fonts false
+\font_sc false
+\font_osf false
+\font_sf_scale 100 100
+\font_tt_scale 100 100
+\use_microtype false
+\use_dash_ligatures true
+\graphics default
+\default_output_format pdf2
+\output_sync 0
+\bibtex_command default
+\index_command default
+\paperfontsize default
+\spacing single
+\use_hyperref false
+\papersize default
+\use_geometry false
+\use_package amsmath 1
+\use_package amssymb 1
+\use_package cancel 1
+\use_package esint 1
+\use_package mathdots 1
+\use_package mathtools 1
+\use_package mhchem 1
+\use_package stackrel 1
+\use_package stmaryrd 1
+\use_package undertilde 1
+\cite_engine basic
+\cite_engine_type default
+\biblio_style plain
+\use_bibtopic false
+\use_indices false
+\paperorientation portrait
+\suppress_date false
+\justification false
+\use_refstyle 1
+\branch mfe
+\selected 0
+\filename_suffix 0
+\color #faf0e6
+\end_branch
+\index Index
+\shortcut idx
+\color #008000
+\end_index
+\secnumdepth 3
+\tocdepth 3
+\paragraph_separation indent
+\paragraph_indentation default
+\is_math_indent 0
+\math_number_before 0
+\quotes_style english
+\dynamic_quotes 0
+\papercolumns 1
+\papersides 1
+\paperpagestyle default
+\tracking_changes false
+\output_changes false
+\html_math_output 0
+\html_css_as_file 0
+\html_be_strict false
+\end_header
+
+\begin_body
+
+\begin_layout Standard
+Iconv reports an error during latex export if a 
+\begin_inset Quotes eld
+\end_inset
+
+nomenclature inset
+\begin_inset Quotes erd
+\end_inset
+
+ contains a character that cannot be encoded using 
+\begin_inset Quotes eld
+\end_inset
+
+
+\backslash
+inputenc
+\begin_inset Quotes erd
+\end_inset
+
+.
+ 
+\end_layout
+
+\begin_layout Standard
+Examples:
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset nomenclature
+LatexCommand nomenclature
+symbol "α"
+description "Greek letter alpha."
+literal "true"
+
+\end_inset
+
+ (uncodable symbol)
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset nomenclature
+LatexCommand nomenclature
+symbol "s"
+description "Latin σ"
+literal "true"
+
+\end_inset
+
+ (uncodable description)
+\end_layout
+
+\begin_layout Standard
+\begin_inset CommandInset nomenclature
+LatexCommand nomenclature
+prefix "σ"
+symbol "s"
+description "Latin s"
+literal "true"
+
+\end_inset
+
+ (uncodable sortkey).
+\end_layout
+
+\end_body
+\end_document

development/autotests/invertedTests

@@ -49,6 +49,9 @@ export/examples/listerrors_(pdf[245]).*
 # (Also fails with Xe/LuaTeX and TeX-fonts -- as expected, see ignoredTests)
 export/examples/ko/splash_(dvi||pdf[23]?)
 
+# iconv fails, if a nomenclature inset contains an uncodable character
+export/export/latex/iconv-error-nomenclature_pdf2
+
 # input encoding tests
 # --------------------
 # Please test and correct!

lib/doc/attic/id_UserGuide.lyx

@@ -28088,7 +28088,7 @@ should appear in nomenclature entries they need to be escaped by adding
 \begin_inset CommandInset nomenclature
 LatexCommand nomenclature
 symbol "\"@, \"|, \"!, \"\""
-description "The quote sign is output by writing ‘ \"\"\"\" '"
+description "The quote sign is output by writing ` \"\"\"\" '"
 
 \end_inset