merge(3p/git): Merge git subtree at v2.29.2

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

third_party/git/t/t0040-parse-options.sh

@@ -23,6 +23,8 @@ usage: test-tool parse-options <options>
     -j <n>                get a integer, too
     -m, --magnitude <n>   get a magnitude
     --set23               set integer to 23
+    --mode1               set integer to 1 (cmdmode option)
+    --mode2               set integer to 2 (cmdmode option)
     -L, --length <str>    get length of <str>
     -F, --file <file>     set file to <file>
 
@@ -42,7 +44,7 @@ Magic arguments
     --no-ambiguous        negative ambiguity
 
 Standard options
-    --abbrev[=<n>]        use <n> digits to display SHA-1s
+    --abbrev[=<n>]        use <n> digits to display object names
     -v, --verbose         be verbose
     -n, --dry-run         dry run
     -q, --quiet           be quiet
@@ -52,7 +54,7 @@ Alias
     -A, --alias-source <string>
                           get a string
     -Z, --alias-target <string>
-                          get a string
+                          alias of --alias-source
 
 EOF
 
@@ -242,7 +244,7 @@ test_expect_success 'Alias options do not contribute to abbreviation' '
 '
 
 cat >typo.err <<\EOF
-error: did you mean `--boolean` (with two dashes ?)
+error: did you mean `--boolean` (with two dashes)?
 EOF
 
 test_expect_success 'detect possible typos' '
@@ -252,7 +254,7 @@ test_expect_success 'detect possible typos' '
 '
 
 cat >typo.err <<\EOF
-error: did you mean `--ambiguous` (with two dashes ?)
+error: did you mean `--ambiguous` (with two dashes)?
 EOF
 
 test_expect_success 'detect possible typos' '
@@ -324,6 +326,22 @@ test_expect_success 'OPT_NEGBIT() works' '
 	test-tool parse-options --expect="boolean: 6" -bb --no-neg-or4
 '
 
+test_expect_success 'OPT_CMDMODE() works' '
+	test-tool parse-options --expect="integer: 1" --mode1
+'
+
+test_expect_success 'OPT_CMDMODE() detects incompatibility' '
+	test_must_fail test-tool parse-options --mode1 --mode2 >output 2>output.err &&
+	test_must_be_empty output &&
+	test_i18ngrep "incompatible with --mode" output.err
+'
+
+test_expect_success 'OPT_CMDMODE() detects incompatibility with something else' '
+	test_must_fail test-tool parse-options --set23 --mode2 >output 2>output.err &&
+	test_must_be_empty output &&
+	test_i18ngrep "incompatible with something else" output.err
+'
+
 test_expect_success 'OPT_COUNTUP() with PARSE_OPT_NODASH works' '
 	test-tool parse-options --expect="boolean: 6" + + + + + +
 '
@@ -399,4 +417,11 @@ test_expect_success 'GIT_TEST_DISALLOW_ABBREVIATED_OPTIONS works' '
 		test-tool parse-options --ye
 '
 
+test_expect_success '--end-of-options treats remainder as args' '
+	test-tool parse-options \
+	    --expect="verbose: -1" \
+	    --expect="arg 00: --verbose" \
+	    --end-of-options --verbose
+'
+
 test_done