Two fixes to the handling of the --bbl option

1. Remove "old/" and "new/" prefixes from the --expand-bbl argument to
latexpand.  Not wanted since we have already changed to the relevant
directory.

2. Allow for the case where the .bbl files are not stored in the repo.
Try to regenerate them on the fly if they are missing.

(Whitespace fixes by Matthieu Moy)

git-latexdiff

@@ -459,24 +459,46 @@ fi
 
 # Shortcut to include bbl
 if test "$bbl" = 1; then
-    oldbbl=("--expand-bbl old/"$mainbase".bbl")
-    newbbl=("--expand-bbl new/"$mainbase".bbl")
+    bblexpand=("--expand-bbl "$mainbase".bbl")
 else
-    oldbbl=("")
-    newbbl=("")
+    bblexpand=("")
 fi
 
 # Create flattened documents and keep for debugging
 if test "$flatten" = 1; then
+    if [ "$bbl" = 1 ]; then
+	if [ ! -f "old/"$maindir$mainbase".bbl" ]; then
+	    verbose "Attempting to regenerate missing old/"$maindir$mainbase".bbl"
+	    (
+		cd old/"$maindir"
+		log_cmd pdflatex0.log pdflatex $latexopt "$mainbase" || compile_error=1
+		log_cmd bibtex0.log bibtex "$mainbase" || compile_error=1
+	    )
+	    if [ "$compile_error" = 1 ]; then
+		die "Failed to regenerate .bbl for old version"
+	    fi
+	fi
+	if [ ! -f "new/"$maindir$mainbase".bbl" ]; then
+	    verbose "Attempting to regenerate missing new/"$maindir$mainbase".bbl"
+	    (
+		cd new/"$maindir"
+		log_cmd pdflatex0.log pdflatex $latexopt "$mainbase" || compile_error=1
+		log_cmd bibtex0.log bibtex "$mainbase" || compile_error=1
+	    )
+	    if [ "$compile_error" = 1 ]; then
+		die "Failed to regenerate .bbl for new version"
+	    fi
+	fi
+    fi
     verbose "Running latexpand"
     (
 	cd old/"$maindir" &&
-	latexpand "$mainbase".tex "${latexpand[@]}" $oldbbl
+	latexpand "$mainbase".tex "${latexpand[@]}" $bblexpand
     ) > old-"$mainbase"-fl.tex \
 	|| die "latexpand failed for old version"
     (
 	cd new/"$maindir" &&
-	latexpand "$mainbase".tex "${latexpand[@]}" $newbbl
+	latexpand "$mainbase".tex "${latexpand[@]}" $bblexpand
     ) > new-"$mainbase"-fl.tex \
 	|| die "latexpand failed for new version"
     verbose_done