git-gui: use shell to launch textconv filter in "blame"

The textconv filters may include multiple arguments and may make use
of unix shell features. To maintain compatibility with 'git blame'
ensure these commands are passed through bash.
Reported-by: NKirill Smelkov <kirr@landau.phys.spbu.ru>
Signed-off-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NPat Thoyts <patthoyts@users.sourceforge.net>

Makefile

@@ -215,6 +215,7 @@ endif
 $(GITGUI_MAIN): git-gui.sh GIT-VERSION-FILE GIT-GUI-VARS
 	$(QUIET_GEN)rm -f $@ $@+ && \
 	sed -e '1s|#!.*/sh|#!$(SHELL_PATH_SQ)|' \
+		-e 's|@@SHELL_PATH@@|$(SHELL_PATH_SQ)|' \
 		-e '1,30s|^ argv0=$$0| argv0=$(GITGUI_SCRIPT)|' \
 		-e '1,30s|^ exec wish | exec '\''$(TCLTK_PATH_SED)'\'' |' \
 		-e 's/@@GITGUI_VERSION@@/$(GITGUI_VERSION)/g' \

git-gui.sh

@@ -128,6 +128,7 @@ set _githtmldir {}
 set _reponame {}
 set _iscygwin {}
 set _search_path {}
+set _shellpath {@@SHELL_PATH@@}
 
 set _trace [lsearch -exact $argv --trace]
 if {$_trace >= 0} {
@@ -137,6 +138,11 @@ if {$_trace >= 0} {
 	set _trace 0
 }
 
+proc shellpath {} {
+	global _shellpath
+	return $_shellpath
+}
+
 proc appname {} {
 	global _appname
 	return $_appname

lib/blame.tcl

@@ -460,7 +460,9 @@ method _load {jump} {
 	}
 	if {$commit eq {}} {
 		if {$do_textconv ne 0} {
-			set fd [open |[list $textconv $path] r]
+			# Run textconv with sh -c "..." to allow it to
+			# contain command + arguments.
+			set fd [open |[list [shellpath] -c "$textconv \"\$0\"" $path] r]
 		} else {
 			set fd [open $path r]
 		}