Build in separate directory fails: funky path contatenation

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POSTGRESQL BUG REPORT TEMPLATE
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Your name : Eric Buddington
Your email address : ebuddington(at)wesleyn(dot)edu

System Configuration
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Architecture (example: Intel Pentium) : AMD K-6

Operating System (example: Linux 2.0.26 ELF) : Linux 2.2.5-ac6

PostgreSQL version (example: PostgreSQL-6.4.2) : PostgreSQL-6.4.2

Compiler used (example: gcc 2.8.0) : gcc 2.7.2.3

Please enter a FULL description of your problem:
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Trying to script the entire compile process (untar to install), I found
that configure barfs if you try to build outside the source dir.

It complains:

--
configure: error: can not find install-sh or install.sh in
/src/build/postgresql-6.4.2
/src/build-src/postgresql-6.4.2/postgresql-6.4.2/src//src/build/postgresql-6.4.2
--

That second path is clearly bogus. Explained somewhat below.

Please describe a way to repeat the problem. Please try to provide a
concise reproducible example, if at all possible:
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/src/build-src/postgresql-6.4.2/postgresql-6.4.2/src/configure
--prefix=/packages/postgresql/6.4.2/any
--exec-prefix=/packages/postgresql/6.4.2
--srcdir=/src/build-src/postgresql-6.4.2/postgresql-6.4.2/src

If you know how this problem might be fixed, list the solution below:
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The problem is visible at src/configure:563:

---
for ac_dir in `pwd` $srcdir/`pwd`; do
---

This is probably where it calculates that inexcusable path. If it tried
just '$srcdir', I believe it would have found the install-sh script.

I know that configure is automatically generated, so this is a bug higher
up in the food chain (possible in autoconf itself?)

- Eric