Disable git terminal prompt during fetch/clone

git fetch operation may prompt user to enter username and password.
This won't be visible to user when repo sync operation since stdout and
stderr are redirected. If that happens, user may think repo is doing
work and likely won't realize it's stuck on user's input.

This patch disables prompt for clone and fetch operations, and repo will
fail fast.

R=gavinmak@google.com

Bug: b/368644181
Change-Id: I2efa88ae66067587a00678eda155d861034b9127
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/438001
Reviewed-by: Nasser Grainawi <nasser.grainawi@linaro.org>
Tested-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>
Reviewed-by: Gavin Mak <gavinmak@google.com>

git_command.py

@@ -313,10 +313,13 @@ class GitCommand:
             cwd = None
         command_name = cmdv[0]
         command.append(command_name)
+
+        if command_name in ("fetch", "clone"):
+            env["GIT_TERMINAL_PROMPT"] = "0"
             # Need to use the --progress flag for fetch/clone so output will be
-        # displayed as by default git only does progress output if stderr is a
-        # TTY.
-        if sys.stderr.isatty() and command_name in ("fetch", "clone"):
+            # displayed as by default git only does progress output if stderr is
+            # a TTY.
+            if sys.stderr.isatty():
                 if "--progress" not in cmdv and "--quiet" not in cmdv:
                     command.append("--progress")
         command.extend(cmdv[1:])

project.py

@@ -2697,6 +2697,19 @@ class Project:
                 )
                 # Continue right away so we don't sleep as we shouldn't need to.
                 continue
+            elif (
+                ret == 128
+                and gitcmd.stdout
+                and "fatal: could not read Username" in gitcmd.stdout
+            ):
+                # User needs to be authenticated, and Git wants to prompt for
+                # username and password.
+                print(
+                    "git requires authentication, but repo cannot perform "
+                    "interactive authentication. Check git credentials.",
+                    file=output_redir,
+                )
+                break
             elif current_branch_only and is_sha1 and ret == 128:
                 # Exit code 128 means "couldn't find the ref you asked for"; if
                 # we're in sha1 mode, we just tried sync'ing from the upstream