The hot-fix brings several improvements for migration script from 1.6 version, fixes for reports and a few more. See changelog for details. Interface to Eventum bug tracker is added. 
 
There is no changes in DB schema (the last changes are in TL 1.7.1). So you can only replace the files of your installation only (and copy config_db and custom_config). 
 
Please, download from  
http://sourceforge.net/project/showfiles.php?group_id=90976&package_id=216115&release_id=562211

 Testlink 1.7.2 changelog

- 0000777: [Test Specification] txt attachment for test case can't be view online. (schlundus)
- 0001054: [Test Specification] IE7 and Attachment downloads (schlundus)
- 0000866: [Custom fields] Assigning keyword in Testcase-specification makes layout jump (schlundus)
- 0001226: [Custom fields] Adding custom field results in error (MSSQL) (schlundus)
- 0001209: [Keywords] Primary key error when adding keywords to test suites. (schlundus)
- 0000960: [Reports, Metrics, Export and Print] Undefined constant link_to_bts in resultsBugs.php (kevin)
- 0001195: [Localization] Help files - German Translation (schlundus)
- 0001112: [Installer] Requirements coverage migration from 1.6.3 to 1.7.0 final (mhavlat)
- 0001125: [Installer] Upgrading database from 1.62 to 1.7 fails (azl)
- 0001227: [Integration with Other Systems] Contribution - Eventum BTS interface (mhavlat)
- 0000558: [Test Specification] Edit Test Case - Bottom "Update" button doesn't line up and white boxes (fman)
- 0001215: [Reports, Metrics, Export and Print] Contribution - patch metric_dashboard.php to only show testplans related to selected testproject (fman)
- 0001063: [Reports, Metrics, Export and Print] In "Requirements based report", Requirement title is shown instead of Testcase title (fman)
- 0000982: [Reports, Metrics, Export and Print] Graphs are out of plot area (mhavlat)
- 0000938: [Reports, Metrics, Export and Print] Overall Build Status and Test Report are WRONG (mhavlat)
- 0001189: [Custom fields] Deleting Custom field gives errors on the screen -- functionality works (fman)
- 0001214: [Database Postgres] postgres reject timestamp (mhavlat)
- 0001206: [Localization] Edit/Delete Requirement Specification Document title might have to modified (mhavlat)
- 0001185: [Reports, Metrics, Export and Print] missing data in test plan print (mhavlat)
- 0001122: [Documentation (ICG, User Manual)] The help file's css of "Test reports and Metrics" (mhavlat)
- 0001131: [Internal issue] Favicon.ico errors in log. (fman)