Fix indexing of $history

cherry-picked from krader1961/fish-shell commit b69df4fe72

Fixes #4353 (regression in indexing of history contents) and introduces
new unit tests to catch bad $history indexing in the future.

tests/history.expect

@@ -30,7 +30,7 @@ expect_prompt
 send "echo start1; builtin history; echo end1\r"
 expect_prompt -re {start1\r\nend1\r\n} {
     puts "empty history detected as expected"
-} unmatched {
+} timeout {
     puts stderr "empty history not detected as expected"
 }
 
@@ -39,7 +39,7 @@ expect_prompt -re {start1\r\nend1\r\n} {
 send "echo start2; builtin history; echo end2\r"
 expect_prompt -re {start2\r\necho start1; builtin history; echo end1\r\nend2\r\n} {
     puts "first history command detected as expected"
-} unmatched {
+} timeout {
     puts stderr "first history command not detected as expected"
 }
 
@@ -53,7 +53,7 @@ expect_prompt -re {start2\r\necho start1; builtin history; echo end1\r\nend2\r\n
 send "history search echo start\r"
 expect_prompt -re {\r\necho start1.*\r\necho start2} {
     puts "history function explicit search succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit search failed"
 }
 
@@ -62,7 +62,7 @@ expect_prompt -re {\r\necho start1.*\r\necho start2} {
 send "history -p 'echo start'\r"
 expect_prompt -re {\r\necho start2.*\r\necho start1} {
     puts "history function implicit search succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function implicit search failed"
 }
 
@@ -71,7 +71,7 @@ expect_prompt -re {\r\necho start2.*\r\necho start1} {
 send "history search --show-time='# %F %T%n' --prefix 'echo start'\r"
 expect_prompt -re {\r\n# \d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\r\necho start2; .*\r\n# \d\d\d\d-\d\d-\d\d \d\d:\d\d:\d\d\r\necho start1; } {
     puts "history function implicit search with timestamps succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function implicit search with timestamps failed"
 }
 
@@ -90,14 +90,14 @@ expect_prompt
 send "history search --exact 'echo goodbye'\r"
 expect_prompt -re {\r\necho goodbye\r\n} {
     puts "history function explicit exact search 'echo goodbye' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit exact search 'echo goodbye' failed"
 }
 
 send "history search --exact 'echo hello'\r"
 expect_prompt -re {\r\necho hello\r\n} {
     puts "history function explicit exact search 'echo hello' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit exact search 'echo hello' failed"
 }
 
@@ -106,7 +106,7 @@ expect_prompt -re {\r\necho hello\r\n} {
 send "history search --exact 'echo hell'\r"
 expect_prompt -re {history search --exact 'echo hell'\r\n} {
     puts "history function explicit exact search 'echo hell' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit exact search 'echo hell' failed"
 }
 
@@ -117,7 +117,7 @@ expect -re {history delete -e -C 'echo hello'\r\n}
 send "echo count hello (history search -e -C 'echo hello' | wc -l | string trim)\r"
 expect -re {\r\ncount hello 0\r\n} {
     puts "history function explicit exact delete 'echo hello' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit exact delete 'echo hello' failed"
 }
 
@@ -139,13 +139,21 @@ expect -re {Deleting history entry 1: "echo hello AGAIN"\r\n}
 send "echo count AGAIN (history search -e -C 'echo hello AGAIN' | wc -l | string trim)\r"
 expect -re {\r\ncount AGAIN 0\r\n} {
     puts "history function explicit prefix delete 'echo hello AGAIN' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit prefix delete 'echo hello AGAIN' failed"
 }
 
 send "echo count again (history search -e -C 'echo hello again' | wc -l | string trim)\r"
 expect -re {\r\ncount again 1\r\n} {
     puts "history function explicit exact search 'echo hello again' succeeded"
-} unmatched {
+} timeout {
     puts stderr "history function explicit exact search 'echo hello again' failed"
 }
+
+# Verify that the $history var has the expected content.
+send "echo history2=\$history\[2\]\r"
+expect -re {\r\nhistory2=echo count AGAIN .*\r\n} {
+    puts "history\[2\] had the correct data"
+} timeout {
+    puts stderr "history\[2\] had the wrong data"
+}

tests/history.expect.out

@@ -9,3 +9,4 @@ history function explicit exact search 'echo hell' succeeded
 history function explicit exact delete 'echo hello' succeeded
 history function explicit prefix delete 'echo hello AGAIN' succeeded
 history function explicit exact search 'echo hello again' succeeded
+history[2] had the correct data